The agreement, signed by U.S. Trade Representative Susan Schwab and Russian Minister of Trade and Economic Development German Gref, paved the way for Russia to become a full member of the WTO.

Describing it as an important milestone in Russia's bid to join the WTO, Schwab said the document signed will be subject to approval through legal procedures in their respective countries.

"I'm pleased that we have concluded this important agreement with Russia's WTO accession negotiations. This is a strong and far-reaching agreement that meets the high standards of President Bush's market-opening trade agenda and moves Russia closer to full integration into the global, rules-based trading system," Schwab said.

She said that the United States will grant permanent normal trade relations (PNTR) to Russia, and U.S. business people will benefit much once Russia becomes a full WTO member.

Russian Trade Minister Gref said "The signing of the agreement is a historic event and a milestone for Russia to integrate into the global economy," adding that tremendous work had been done by both sides to conclude the agreement.

According to Schwab, Russia's tariff commitments include participation in the Information Technology Agreement, which will result in the duty-free entry of IT products such as computers and semiconductors.

Russia has also agreed to substantially reduce its tariffs on both wide body and narrow body of civil aircraft and parts, and the country's overall bound tariff rate on industrial and consumer products will average around eight percent.

With respect to other non-tariff barriers, the agreement sets out an understanding on procedures for importing technology products with encryption. And Russia will reduce export duties on ferrous (steel) scrape and eliminate its export duty on copper cathode.

The bilateral market access agreement also includes important provisions that will strengthen intellectual property rights (IPR) protection in Russia.

Gref said that Russia had been committed to IPR protection, which is in the interest of the country, adding that Russia will implement what has been agreed in the document.

Russia has been negotiating its terms of accession to the WTO, and previously the General Agreement on Tariffs and Trade, since 1993. The next step in Russia's accession process is completion of multilateral negotiations.

"I am pleased to work with the Russian side on the last stage of the journey," Schwab said.

Specialist detectives launched an investigation as the 43-year-old lay in bed in the central University College Hospital in a serious but stable condition, fighting what an expert said was poisoning by thallium, a toxic metal.

Friends of Litvinenko said they were in no doubt that the FSB was out to get the outspoken defector, who was granted political asylum in Britain in 2001.

A spokesman for London's Metropolitan Police told AFP: "Officers from the specialist crime directorate are investigating a suspicious poisoning.

"The inquiry is continuing and there's no arrest at this stage."

If Russia's security services were behind the alleged poisoning, it would not be the first time that they have tried to silence critics on the streets of London.

In 1978, Bulgarian dissident Georgi Markov was stabbed in the leg while walking across London's Waterloo Bridge by a man with an umbrella which fired a ricin pellet. Markov died in hospital three days later.

KGB defectors including Oleg Gordievsky have since confirmed that the Soviet intelligence agency was behind the killing.

More recently, Ukrainian prosecutors said in September that the dioxin which poisoned Ukrainian President Viktor Yushchenko during 2004 elections was made in the United States, Britain or Russia.

Yushchenko still bears facial disfigurement after falling ill during his presidential election campaign in September 2004, the day after he had dined with officials from the Ukrainian security services.

Litvinenko fled to Britain after blowing the whistle on an alleged FSB plot to assassinate Russian business oligarch Boris Berezovsky, who is also now living in Britain.

Litvinenko reportedly fell out with Putin when the president was head of the FSB in the late 1990s.

He claimed the agency was linked to apartment bombings in 1999 which killed around 300 people and were blamed on the Chechens, one of the reasons then-prime minister Putin sent Russian troops back into Chechnya, a popular war that propelled him into the presidency in 2000.

Politkovskaya, a long-term thorn in the Kremlin's side over the war, who was shot dead in her apartment in October, prompting an international outcry, was reportedly a friend of Litvinenko.

The Sunday Times said the former agent had met an Italian called Mario at the sushi restaurant.

"I ordered lunch but he ate nothing," the weekly quoted Litvinenko as saying, without stating how or when he had spoken to the paper.

"He appeared to be very nervous," he added. "He handed me a four-page document which he said he wanted me to read right away.

"It contained a list of names of people, including FSB officers, who were purported to be connected with the journalist's murder."

But Litvinenko added he was not in a position to accuse Mario of involvement in the poisoning, the paper said.

The Mail on Sunday said Litvinenko was in hospital under armed guard, was struggling to speak and had only a 50 percent chance of survival.

He had kidney damage, was constantly vomiting and suffered an almost total loss of white blood cells, The Sunday Times added.

The paper quoted a medical report which showed he had three times the maximum safe limit of thallium in his body.

Clinical toxicologist John Henry, who examined Litvinenko on Saturday, said the former spy was "quite seriously sick".

"There's no doubt that he's been poisoned by thallium, and it probably dates back to 1 November, when he first started to get ill," he told the BBC.

"It is tasteless, colourless, odourless. It takes about a gram... to kill you."

A friend of Litvinenko, Alex Goldfarb, said outside the hospital: "He looks terrible. He looks like a ghost actually. He lost all his hair. He hasn't eaten for 18 days."

He added: "I think this is the work of the Russian secret service."

A leading Chechen separatist in London, Akhmed Zakayev, told Sky News television he believed Litvinenko's illness was due to "the condoning and lacklustre attitude of the Western governments to the state terrorism policy perpetrated by Russia". He described what had happened as a "terrorist attack".

The Russian embassy in London was unavailable for comment.

Police spokesman Josef Brinker said the gunman went into Geschwister Scholl school in Emsdetten, near the Dutch border, at about 9:30 a.m., shortly after morning classes started, and opened fire.

Police cleared the school and ensured all students in the building were taken to safety.

It happened in Ho Chi Minh City in Vietnam before the president was to fly to Jakarta, Indonesia.

The glitch left officials scrambling to accommodate dozens of traveling staffers. Most were getting seats on a press charter aircraft.

The White House is hopeful the 747 will be repaired before the next leg -- from Jakarta to Hawaii. If it isn't, Bush's Boeing 757 may have to make refueling stops along the way.

Preliminary tests identified the source of the outbreak as the highly contagious norovirus, which had struck several guests just before they boarded the cruise Nov. 3 in Rome, Carnival officials said. More than 530 guests and 140 crew reported to the ship's infirmary with similar symptoms during the 16-day voyage.

Passengers who fell ill during the cruise said they received over-the-counter anti-diarrheal medication and pills or an injection to ward off nausea in the ship's infirmary, and had been quarantined in their cabins.

"They brought us 7-Up, bottled water, ice and a diet of rice, though you didn't feel like eating," said Jim Lankes, 48, of Phoenix. Lankes and his 45-year-old brother both got sick when the ship was docked in Barcelona, Spain.

Crews scrubbed the ship's handrails and utensils, offered disinfecting hand gel and halted the self-serve buffets after the outbreak started. Even plastic menus were wiped clean, said Pedro Carreras, 51, of McDonough, Ga.

Most cruise activities and excursions continued as scheduled, passengers said, though the crew's illness disrupted some personal services.

"Our cabin steward was struck, and we didn't have anybody to clean our cabin for five days," said Pamela Stupnik of Pueblo, Colo. She said she and her husband spent two days vomiting in their cabin.

A team from the U.S. Centers for Disease Control boarded the cruise when it docked in St. Maarten to oversee the cleaning operation and try to determine what caused the outbreak, Carnival said.

Norovirus is a group of viruses that cause stomach flu symptoms such as diarrhea, vomiting and stomach cramps, according to the CDC. The illness usually lasts one to two days without any long-term health effects. It spreads through contaminated food or liquids, by touching contaminated surfaces or objects and then placing that hand in one's mouth, or through direct contact with someone who is infected and showing symptoms.

The Liberty, which has room for 2,974 travelers, had been scheduled to set sail again Sunday afternoon on a six-day Caribbean voyage, but Miami-based Carnival delayed its next departure until Tuesday so crews could have extra time to disinfect the ship.