Documents and captives seized by British troops in Basra reveal that the recruits were arriving in Baghdad from Muslim countries including Egypt, Saudi Arabia and Yemen as little as ten days before the war began.

They came to wage jihad against the Western military, and provided some of the fiercest resistance as the coalition advanced northwards. Survivors are still mounting occasional attacks in Baghdad and other cities.

US officials are seizing on the guerrillas’ presence as evidence of links between Saddam and Osama bin Laden’s al-Qaeda terrorist organisation — links that the Bush Administration has long cited as a justification for the war.

The foreign fighters provide a “direct tie between Saddam Hussein and terrorist organisations”, a Pentagon spokeswoman said last night.

British investigators are more cautious, but one officer involved in questioning the survivors told The Times: “These are not just zealots who grabbed a gun and went to the front line. They know how to employ guerrilla tactics so someone had to have trained them. They are certainly organised, and if it’s not bin Laden’s people, its al-Qaeda by another name. But they certainly came here to fight the West.”

Identity documents show the men came from Algeria, Tunisia, Egypt, Syria, Morocco, Yemen and Saudi Arabia. The Americans say they have also captured Chechens fighting with Fedayin units close to Baghdad. The guerrillas were also in a different league from the rag-tag collection of volunteers who arrived in Baghdad before the war on buses from Jordan and Syria.

The “foreign legion” stunned British troops with their skills and fanaticism.

The commander of a tank squadron described how four hours after they had smashed their way past the militants’ last stronghold in Basra University last week, two men who had laid among their dead colleagues for all that time suddenly jumped up and ran towards him with a grenade in their hands, trying to reach the British crew 50 yards away.

“I have never seen such fanatical behaviour. It was truly chilling,” the commander said. “Our machinegun was pointed right at them. They knew they were going to die, but they just kept running at us and shouting, determined not to throw the grenade but to jump on to the tank and detonate it while still holding it.”

Documentary evidence found by British troops in Basra shows that several hundred of the fighters were brought to Iraq using a variety of official documents provided by the Baghdad regime.

Many posed as students, enlisting at the university’s school of Koranic studies or in its language school. Airline ticket stubs and other paperwork show there was a rush of new recruits in early March, and that they were still arriving in Iraq ten days before the war began. Some of their Iraqi visas list “jihadi” in the space giving the passport holder’s reason for visiting Iraq.

A lot of the documentary evidence, which also includes identity cards, driving licences and personal correspondence, was stashed in a holdall found in a reception building at the entrance to Basra University, where one of these militant groups had its headquarters.

Crucial evidence has also come from a 26-year-old Syrian teacher, one of roughly a dozen foreign fighters taken captive in Basra. He was found in the wreckage of the reception centre after a tank shell had punched a gaping hole in it from near point-blank range. Four others lay dead around him. He too tried to feign death but a British soldier noticed him breathing.

“He lashed out at us, then when it was clear we had him in our grip he begged us to execute him. ‘Shoot me, shoot me he kept saying. ‘I want to die’, ” the commander said. “He told us he had come to fight the West and be a martyr, so he had failed.”

After British troops gave him water, the Syrian began to talk. The commander said: “He told us he was in Basra to get medical treatment for diabetes. Then he said he was a student at this university. We found his passport and he was one who had ‘jihadi’ stamped on his Iraqi visa. He entered Iraq on March 8 from Jordan.”

All these documents are now being closely studied by British Intelligence, along with personal correspondence found among the ruins.

One letter, sent from Egypt, is from a father to a son, praising his mission. Another, again from Egypt judging from the postage stamps on the blue envelope, is a letter from a wife writing about their children. Enclosed is a photograph of their two children. Scrawled on the back in blue felt-tip pen is a message reading: “For those closest to me I will give everything.”

It is not known if the man who wrote that is among the dead or one of those in custody.

The foreign fighters were given money, and operated alongside Fedayin units rather than Baath party militias, and never the regular army. What is now apparent is that it was these foreign fighters who led the resistance inside Iraq’s second city.

Weaponry found shows they were well-supplied with rocket-propelled grenades and heavy machineguns, and that the tactics they employed proved that they knew how to use such hardware to attempt to disable tanks and armoured personnel carriers.

President Bush last night urged Syria to close its borders to fleeing followers of Saddam and turn over any who have already found “safe haven” in Iraq’s western neighbor.

He said that he expected the Syrians “to do everything they can to prevent people who should be held to account from escaping in their country”.

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