In Jenin, soldiers came under heavy fire from gunmen holed up in a house in the city during an operation to arrest them. The army declined to comment on whether there were Israeli casualties in the raid.

Palestinian residents said a fierce gun battle was under way at the house where a group of gunmen from the Islamic Jihad militant group were trading fire with troops surrounding the building.

Earlier on Thursday, Palestinian gunmen shot and wounded two Israeli motorists near a Jewish settlement in the northern West Bank. The Israelis were taken to hospital with light to moderate wounds, the army said.

"This international undercover investigation revealed an insidious network that engaged in worldwide trafficking in child pornography, including live molestations of children transmitted over the Internet," U.S. Attorney General Alberto Gonzales said in a statement released ahead of a visit to Chicago.

Authorities have identified seven child victims, including an infant whose molestation in April by a suburban Chicago man was transmitted live via an Internet chat room to a co-conspirator who used the screen name "Big_Daddy619."

Four of those charged allegedly molested the children, making the resulting images available in the chat room called "Kiddypics & Kiddyvids," that facilitated trading of thousands of images and videos, the statement said.

Manufacturing child pornography carries a minimum 15-year prison sentence, while the other charges call for minimum sentences of at least five years.

"Interoperability is mentioned not only in relation to the common use of large-scale IT systems but also with regard to possibilities of accessing or exchanging data, or even of merging databases," according to the opinion. "This is regrettable since different kinds of interoperability require different safeguards and conditions."

The supervisor is also a proponent of the introduction of a so-called purpose limitation principle, which would require data to be processed fairly and lawfully and for a legitimate purpose. New data protection safeguards are therefore needed, Hustinx added.

The supervisor also hit out at the use of biometrics as unique identifiers for European citizens within databases, saying that fingerprint or DNA identifications are too inaccurate and can facilitate the unwarranted interconnection of databases.

"It is regrettable that the protection of personal data has not been explored sufficiently as an inherent part of the improvement of the interoperability of relevant systems," Hustinx said.

"The EDPS suggests adding to this communication a more consistent analysis on data protection, including privacy-enhancing technologies to improve both effectiveness and data protection," he added.

Two of the six patients were critically ill and the other four remained in serious condition in the intensive-care unit of Northwick Park Hospital, an official at the northwest London hospital said.

The men, who had all been healthy, were admitted on Wednesday evening after suddenly falling ill while taking part in the drug trial at the independent research unit in the hospital compound.

Doctor Hanke said TeGenero was "devastated" at the "shocking developments" in the testing of its drug, which the firm identified as TGN1412.

Asked by reporters whether the company had apologised to the men's families, he replied: "Yes."

Hanke also said the drug had shown no adverse side-effects previously and the testing had been done to regulatory standards.

Initial research into the new medicine started in 1997 and it had been in development since 2000 but testing had now been halted, Hanke added.

The Times said senior doctors were concerned that all six victims had been given the experimental drug at the same time.

The newspaper said this went against guidance in "The Textbook of Pharmaceutical Medicine", which advises that such practices can be "very difficult to manage" and "put subjects at unnecessary risk."

Two other men also participated in the clinical trial -- all eight men were paid volunteers -- but escaped unscathed after being given a placebo.

One of the survivors, Raste Khan, 23, described the horror that befell six of his fellow human guinea pigs.

"First they began tearing their shirts off complaining of fever, then some screamed out that their heads felt like they were going to explode," Khan told The Sun tabloid on Thursday.

"After that they started fainting, vomiting and writhing around in their beds," he recalled.

Relatives and girlfriends of the victims also revealed details about their loved-ones' ordeal as they prayed for their recovery.

Ryan Wilson, 21, begged doctors to put him to sleep because he was in so much pain, his sister-in-law Jo Brown, 24, told The Sun.

The trainee plumber suffered heart, lung and kidney failure.

"His head had swollen to nearly three times its normal size. His neck was the same. It was wider than his head and his skin had turned a dark purple," Brown said.

Myfanwy Marshall, 35, tearfully said her boyfriend, a 28-year-old barman whose name has not been revealed, looked like the "Elephant Man".

"They haven't got a cure," she told BBC News.

"This is a drug they have never tested on humans before so they don't know what they are dealing with. It's completely messed up their vital organs."

Britain's medicines watchdog halted the clinical trial on Wednesday and sounded an alert to its equivalent bodies across the
European Union.

The Medicines and Healthcare products Regulatory Agency is currently investigating what went wrong with help from the Metropolitan police.

Surgeons had to remove a portion of the women's abdomen and perform reconstructive surgery in removing the tumour, the health officials in the northern region of Vizcaya said Thursday.

The patient, said to be clinically obese, was not identified.

Although weighing as much as a normal adult woman by itself, the tumour was less than half the size of the largest ever recorded to be removed intact.

In 1991, a surgeon at California's Stanford University Medical Center removed a multicystic ovarian mass weighing 302 pounds (138 kilograms), which Guinness World Records holds to be the biggest ever.

The woman survived and, according to Guinness World Records, she "left the operating theater on one stretcher and the cyst left on another."

Protesters object to new two-year job contracts for under-26s which employers can break off without explanation.

President Jacques Chirac has appealed for talks, but said the new law was important to fight unemployment.

Protests turned violent on Tuesday when police clashed with students holding a sit-in outside the Sorbonne University.

Interior Minister Nicolas Sarkozy met with police and the protest's organisers to try to ensure a peaceful march on Thursday, ministry officials said.

More demonstrations are planned for Saturday, with trade unions calling up to a million people to the streets.

Unemployment rates

Students fear the First Employment Contract (CPE), passed into law last week, will erode job stability, in a country where more than 20% of 18 to 25-year-olds are unemployed - more than twice the national rate.

President Chirac has called for dialogue between ministers and labour leaders, but union officials say they will not enter into talks until the CPE is suspended.

The government of Prime Minister Dominique de Villepin proposed the law to help youths in the French suburbs who took to the streets last year, many unhappy with the lack of employment opportunities.

If the recent troubles awaken memories of student demonstrations in May 1968, the scale, demands and context of these protests are rather different, says the BBC's Caroline Wyatt in Paris.

Now it is the French middle-class, the country's future elite, expressing its fears about the present and the future.

However, the worry for the French government is that, as in May 1968, French students are expressing wider disenchantment with a government that is seen as remote and out of touch, our correspondent adds.

Student leaders said more than 300,000 marched across France and that 64 of the country's 84 universities had been hit by the protests on Thursday. Officials reported lower numbers.

The protests could hurt the conservative Villepin's hopes of running for president in 2007. He says the law will help reduce unemployment among the young, now running at 22.8 percent, more than twice the overall national rate.

Street protests can make or break governments in France. Protests in 1995 badly undermined the then conservative Prime Minister Alain Juppe, who lost snap elections two years later.

Police fired teargas after 100 students briefly occupied a town hall in the western city of Rennes on Thursday. Thousands of students marched in the Mediterranean port city of Marseille and in Bordeaux in the southwest.

In Paris, police in riot gear fired teargas at several dozen youths pelting them with stones in a neighborhood dotted with government ministries. Student leaders said about 120,000 marched across the capital.

BOUTIQUES CLOSED

Nearby boutiques and the elite Sciences Po university closed as a precaution as the protests signaled hardening opposition.

Opinion polls show Villepin's popularity has tumbled during the biggest test of his 10 months in office.

"Chirac, Villepin, Sarkozy, your trial period is up!" read one banner in Paris, referring to President Jacques Chirac, his prime minister and Interior Minister Nicolas Sarkozy.

"Of course we're against (the law). It will enable the bosses to fire people without any cause," said high school student Pedro Amorim, 17.

Some students with "anti-CPE" daubed on their faces, a reference to the so-called "First Job Contract" that allows employers to dismiss workers under 26 during a two-year trial period without having to give a reason.

Student and union leaders have spurned an offer of talks over the law from Villepin, who railroaded the measure through parliament. They say opposition will grow until the prime minister backs down.

"I am open to dialogue within the framework of the law and to improve the First Job Contract," said Villepin.

But Villepin has vowed to stand firm over the law. "I will do it to the end because I believe in this measure," Villepin said in an interview with Paris Match magazine.

With no end in sight to the standoff, ministers have offered six-monthly reviews of the law in an effort to defuse tensions.

"Perhaps it isn't the best solution, perhaps we could improve it, but at least we're moving forwards," Finance Minister Thierry Breton said on RMC radio.

Trade unions plan another day of action on Saturday and hope to top the one million protesters they estimated took part in the March 7 protests. Police estimates were half that figure.

Sarkozy, who took a tough line during suburban riots last year, warned when he met police and student leaders earlier this week that troublemakers could hijack the protests.

France's unemployment rate is one of the highest in Europe at 9.6 percent and more than twice that for under 25-year-olds. It tops 40 percent in some run-down neighborhoods.