The report, released Thursday, says that more than half of the lake's drop in 2004 and 2005 is attributable to the Owen Falls dams in Uganda, across the only outlet for the mountain-fringed lake.

In breach of an international agreement, the dam's operators have been releasing more water than the lake can sustain, it charges.

The reason, says the report, is to maintain sufficient flows of water over the dam's turbines and keep the lights on in Uganda.

"The resultant over-release of water... is contributing to the severe drop in water level in Lake Victoria," says the report, written by Daniel Kull, a hydrological engineer based in Nairobi, for International Rivers Network, a US green group.

The Owens Fall hydroelectric project dates back to 1954.

Until then, the lake spilled out over a natural rock weir, to form the Victoria Nile, which eventually becomes the White Nile.

Britain, Uganda's colonial power, blasted out the weir and replaced it with the first dam, now called the Nalubaale dam, thus effectively transforming Lake Victoria into a vast hydroelectric reservoir.

At the time, engineers agreed a common-sense formula that the flow going through the dam should mimic that of the flow that went over the weir, a rate that ranged from 350 to 1,700 cubic metres (12,250-59,500 cu. feet) per second depending on the water depth in the lake.

The formula, called the "Agreed Curve", remains in force today under a treaty with Egypt, the downstream user of most of the water from the Nile.

In 2000, Uganda built an extension to the Nalubaale dam, called the Kiira extension, to generate more power. The scheme was backed with money by the World Bank, a favourite target for environmentalists for its traditional favouring of big hydro projects.

The turbines are located below those of Nalubaale, using the same "head", or water drop, which is channelled via a 1.3-kilometre (one mile) long canal.

But the demands of the Kiira extension, magnified by a reduction of inflow to Lake Victoria caused by a 10 percent fall in regional annual rainfall and tributary flow, have made it "difficult, if not impossible" to adhere to the Agreed Curve, says Kull.

According to his calculations, 55 percent of the severe drop in Lake Victoria's levels in 2004 and 2005 was due to letting out too much water to feed the Nalubaale and Kiira turbines. Only 45 percent of the fall could be blamed on the drought.

The report raises serious doubts about Uganda's overwhelming dependence on the big dams, given that global warming may lead to drier conditions and lower the lake levels further still.

"It is unknown if Lake Victoria will recharge to the high levels and outfloow experienced during 1961-2000, and if such a recharge could occur, whether it would be in the next years or only in 100 years," it says.

Frank Muramuzi, a member of a Ugandan NGO, the National Association of Professional Environmentalists (NAPE), said the dam complex "is now pulling the plug on Lake Victoria, with implications for millions."

Asked to respond to the report, Ugandan Information Minister James Nsaba Buturo said on Wednesday: "We have no evidence at all that the second dam is the cause of the low water levels. What we have from experts is the prolonged drought as the reason for the low water level."

He added: "Uganda is open to any advice if what we think is the cause is not what it is."

Patrolling the 962,652 entries in the English Wiki - more than double the number a year ago - its idealistic volunteers found other examples of "politically motivated editing" emanating from Washington. In one case, an intern for Democratic representative Marty Meehan deleted a reference to his broken promise to only serve four terms. In another, the office of Senator Norm Coleman deleted an unflattering reference to voting with President George Bush 98% of the time in 2003, despite running as a moderate the year before. Wikipedia took draconian action: all computers connected to servers at the House of Representatives were temporarily denied access to the site.

Computers linked to Canada's House of Commons and the German Bundestag also fiddled with entries, according to Wikipedia. But Jimmy Wales, the Florida-based founder who was embarrassingly exposed for tweaking his own entry, said no suspicious activity had yet been recorded on the computers of Westminster and Whitehall.

Why do our slow-witted special advisers twiddle their thumbs while websavvy idealists write their bosses' biographies? The Guardian could help. I bring up Tony Blair's entry. It appears a perfect example of a Wiki entry: accurate, informative, well-sourced and neutral in tone. But every choice of fact is a subjective act. And there's one our Tone wouldn't like: "Euan Blair received widespread publicity after police found him 'drunk and incapable'." C'mon guys, the kids are off limits. Snip. I cut it out.

"While the Blairs have stated that they wish to shield their children from the media, they have not always been able, or willing ... " Hang on, "willing"? What does that imply? Cut. Save. Refresh page. Tony's Wiki entry is now a lot shinier.

Time to buff up the Guardian. The stereotypical Guardian reader is, Wikipedia explains, a lentil-munching, sandal-wearing lefty. "Like most stereotypes, to some extent this one is both inaccurate and outdated." Let's get rid of "to some extent", eh?

I add some positive spin about our rising circulation. Hang on, there is someone missing from the list of "notable regular contributors (past and present)". Ian Aitken, Julian Borger, Emma Brockes: excellent, excellent. But no "Patrick Barkham". I slip the name in. It looks nice, if suspiciously anomalous.

Ah, the sweet power of the spin doctor (tempered by the growing anxiety that a volunteer will hunt me down and attack me with worms or bots or turn my Mac into a zombie computer). Wikipedia records the internet protocol address of the computer on which every edit occurs. They could easily trace my edits to the Guardian. Its volunteers cleverly trapped the US spinners by sending emails to their offices. When they received replies, they found the IP addresses contained in the emails matched those of the dodgy editors.

Time to phone Wikipedia. Does the furore over the politicians gilding their own lilies undermine its credibility? "It's more damaging to the persons involved," says Mr Wales. "We were able to catch these bad edits very quickly and good edits were incorporated very quickly."

The site is still smarting from bad publicity about the biography of the US journalist John Seigenthaler, which incorrectly linked him to the Kennedy assassinations. The libellous allegations were not spotted for months before they were removed, leading to criticism about its reliability.

Mr Wales says the "whitewashing" editors from Washington are treated "just like editors from a grammar school. If they behave themselves, that's fine. If not, they get blocked."

What does Wikipedia rule on people adding gloss to their own entries? "It's not absolutely forbidden to edit an article you're involved in but it's not considered good practice," says a UK spokesman, David Gerard.

Marty Meehan recanted. "It was a waste of energy and an error in judgment on the part of my staff to have allowed any time to be spent on updating my Wikipedia entry," he said.

And so must I. Shamed by my crass attempts to subvert the democratic goal of a free encyclopedia on the internet, I return and remove my "bad edits" to leave the pages just as they were. Will the world's spin doctors suffer similar pangs of conscience?

Chinese human rights defenders have been fasting to show support for Yang, a rural campaigner, taking turns at not eating for 24 or 48 hours. An Aids campaigner, Hu Jia, one of the leading figures in the protest, said Yang went missing after he tried to protest at Zhongnanhai, China's heavily guarded seat of power near Tiananmen Square.

Mr Hu said: "We know that at six o'clock yesterday he was at the Xicheng district police station, but we do not know where he is now. We cannot get hold of him."

Another protester, Qi Zhiyong, who lost a leg in the 1989 Tiananmen massacre, had gone to look for his colleague but was dragged to his home by police. Mr Hu's own home was under surveillance.

The Beijing government has been trying to contain increasing social unrest, sparked by public anger over issues ranging from land grabs without adequate compensation to official corruption and a yawning wealth gap. The hunger strike takes place as pressure mounts on human rights campaigners. The latest furore over Western web firms in China comes shortly after Google bowed to Beijing by blocking politically sensitive terms on its new China site.

The veteran rights activist Liu Xiaobo said Yahoo had co-operated with Chinese police in a case that led to the arrest in 2002 of Li Zhi, who was charged with subverting state power and jailed for eight years. Yahoo said it had to obey local laws.

Press freedom watchdog Reporters Without Borders insisted Yahoo knew it was helping to arrest dissidents.

In September, Yahoo was accused of helping authorities identify Shi Tao, who was sentenced last April to 10 years in prison for leaking state secrets abroad.

The recent clampdown has seen the dismissal of the editor of the outspoken Beijing News. Chen Jieren, the chief editor of the Public Interest Times, was reportedly sacked this week over criticism of authorities.

Many opt for carbon monoxide poisoning in sealed vehicles, often in secluded or scenic areas, like four young men who died while watching the sun rise from a car at the foot of Mount Fuji. The men met for the first time just hours before their death.

The latest statistics will likely lead to more demands for monitoring of cyberspace, including renewed calls to ban the word "suicide" from search engines. Net service providers already work with the police and there are signs the group-suicide phenomenon may have peaked. But Yukio Saito, who runs Japan's largest telephone helpline, cautions against complacency. "People will always find a way to end their lives if they want to. The wider issues must be tackled."

In Japan, 94 people took their own lives every day in 2003, setting a record of 34,427 that broke the previous high of 33,048, in 1999. Since the Asian crash of 1997-8, when the statistics jumped 35 per cent, suicides have claimed more than 220,000 lives, approximately the population of Derby. A suicide manual that lists effective ways of ending it all - including hanging, electrocution and pills - has sold more than a million copies. In true Japanese style it rates these methods in terms of the pain and trouble they cause to others; predictably, jumping in front of a train is given a maximum rating of five.

The dramatic rise in suicides forced the health ministry to bring out a package of proposals at the end of 2002, including a drastic boost in mental healthcare facilities. But Japan still has far fewer psychiatrists than other advanced countries, and family doctors routinely misdiagnose mental illness. A health ministry survey found that more than half of the workers recognised as having committed suicide due to work-related stress between 1999 and 2002 had been working at least 100 hours overtime a month. "This is a suicide epidemic," says Mr Saito. "We are not doing enough to help people who are suffering in silence."

Japan is not unique. South Korea has also experienced a wave of suicide pacts, and Ireland has seen a 45 per cent increase in suicides over the past decade. But, at 24.1 per 100,000 people, Japan has the highest per-capita suicide rate in the developed world.

Nearly 8,000 people in their twenties and thirties killed themselves in 2003, making suicide one of the leading causes of death for young Japanese. Many of these youngsters are drawn from the ranks of hikkikomori, social recluses who have locked themselves in their rooms, sometimes for years on end.

Many are linked to the outside world only through the electronic umbilical cord of their computers, which they use to find like-minded folk. Dozens of young Japanese can be found every day discussing suicide on online chat rooms. A typical message reads: "If you are thinking about killing yourself, please reply." Another says: "I'm in my early twenties and I want to die easily. I can go anywhere in Japan." Fittingly, perhaps, one of the last acts of the suicidal is often to e-mail a friend or relative. Several times in the past two years the police have stumbled on semi- asphyxiated young people just in time, after similar messages were sent.

More than 80 years after the discovery of the tomb of Tutankhamun, Egypt's Supreme Council of Antiquities has stunned the world of Egyptology by revealing that another tomb has been found, just four metres away from Tutankhamun in the Valley of the Kings.

For a long time it was thought that the valley, opposite the modern city of Luxor and the source of many of the most famous discoveries, had given up all of its secrets.

The discovery was the work of a team of American archaeologists from the University of Memphis led by Otto Schaden.

"It's very, very exciting," said Patricia Podvorzski, curator of Egyptian Art at the University of Memphis. "It was completely unexpected, so long after the discovery of Tutankhamun's tomb. Many archaeologists said the valley was done 100 years ago." Dr Schaden's find is the 63rd tomb to be opened in the valley.

The newly discovered 18th-dynasty tomb contains five mummies in intact sarcophagi with coloured funerary masks, along with more than 20 large storage jars sealed with pharaonic seals, according to Zahi Hawass, head of the Supreme Council of Antiquities.

The sarcophagi are carved in human form, like Tutankhamun's. The tomb is rectangular, and the wooden sarcophagi are surrounded by the jars, which seem to have been placed haphazardly, suggesting that the burial had been completed quickly, according to Dr Hawass.

Dr Schaden has been working in the valley on the Amenmesse Tomb Project, a minor tomb of the 19th dynasty, for many years. "They had finished clearing up that tomb and had started to dig down to the bedrock in front of the entrance," said Dr Podvorzski. "They were looking for foundation deposits - the models of tools, vessels and other things that were put around the tomb of a king to assure the permanence of the structure. While doing that they found workmen's huts made of dry stone and dating from the 19th dynasty. I believe they were in the process of dismantling the huts when they found the new tomb."

It was a very similar chain of events that led to the discovery of Tutankhamun's tomb in 1922. That, too, had been covered by ancient workmen's huts. "That was why the tombs didn't get robbed," added Dr Podvorzski. "The ancient Egyptian tomb robbers saw the huts and assumed there was nothing underneath them."

Although the discovery came as a huge surprise, there had been a suspicion that something else might be found. "Some time ago a British team did remote sensing around the tomb and said they thought there might be something down there," said Dr Podvorzski.

Details of the find are expected to be announced officially by Egypt's Supreme Council of Antiquities today, including possibly the identities of the occupants.

Kent Weeks, an American archaeologist, said the tomb was a single chamber, probably intended for a single mummy. Some or all of the other sarcophagi could have been put in later. He added that photographs of the tomb suggested it did not belong to a king. "It could be the tomb of a king's wife or son, or of a priest or court official," he said. "It clearly proves that the Valley of the Kings is still not exhausted. There are probably many more tombs to be found in it."

Whatever the new tomb may contain, its fate is certain: Egypt's policy on undisturbed tombs is clear. "This stuff will stay in Egypt," said Dr Podvorzski.