US troops search 'London ricin camp'

American troops have begun searching a terrorist camp in north-eastern Iraq they believe is the source of a deadly poison found in London this year.

The Pentagon's top general says the compound was used by the group Ansar al-Islam, which has links with Osama bin Laden's al Qaeda network.

General Richard Myers, head of the US chiefs of staff, believes a biological weapons development programme was used to make the toxin ricin, traces of which were uncovered in a raid on a flat in Wood Green in January.

General Myers said American forces were now examining documents and laptop computers found in the camp, which was captured late last week.

General Myers said last night: "We think that is probably where the ricin that was found in London came from. At least the operatives and maybe some of the formulas came from this site."

The camp, which borders Iran and was in a remote part of Iraq beyond the control of Saddam Hussein, was pounded by British and American aircraft and missiles for several days before it was attacked by American special troops and about 6,000 Kurdish allies.

At least 150 members of Ansar al-Islam were reported killed in the attack. The camp is believed to be riddled with underground tunnels that may take at least a week to search. Four Algerian men were arrested in the raids in London, during which an alleged ricin laboratory was found.

Traces of the substance, which is made from castor oil beans, were also found at a Paris railway station this month.

American intelligence has long claimed that the suspects have ties to Abu Mussab al Zarqawi, a Jordanian who is described as Bin Laden's top biowarfare expert.

There were also reports that the ricin was to be used to poison the food of British troops.

Fears were raised last week that Saddam Hussein may be preparing to use chemical weapons after Huda Salih Mahdi Ammash, the scientist who runs his chemical warfare programme, was shown on Iraqi TV next to the dictator at a cabinet meeting.

Al Zarqawi was badly injured in the US invasion of Afghanistan and was reported to have been given medical attention in Baghdad. He is thought to be the mastermind-of a plot revealed by Tony Blair in October to use a "dirty bomb" or poison gas in Britain. He is also wanted for the murder of an American diplomat in Jordan last year.

In Afghanistan, al Zarqawi worked with a hand-picked group of young Muslim extremists experimenting with poisons, that including ricin.

Film of the toxins being tested on animals was captured by American troops in Afghanistan, and there are reports it was also used on a human guinea-pig who later died.

He is also said to have worked on other biological and chemical weapons and leads his own terrorist cell, calling itself al-Tawhid.

After training, several of the recruits were reported to have been dispatched to Europe.