The move, announced yesterday, came as Hans Blix, the chief United Nations weapons inspector, appeared to undermine Washington and London’s main justification for the war by implying that there may be no banned weapons inside Iraq.

The Pentagon’s decision to send its own search team was in open defiance of calls last week by Tony Blair and the UN for independent inspectors to conduct the hunt, and significantly increased tensions between London and Washington over the effort to find Saddam Hussein’s “hidden weapons”.

On Wednesday, President Bush called for sanctions on Iraq to be lifted. Under existing resolutions, lifting sanctions is contingent on Iraq being declared free of weapons of mass destruction.

Continuing tensions over Iraq were also evident inside the EU yesterday. Tony Blair abruptly left the Athens summit before a photocall of EU leaders, each clutching an olive branch, lined up in front of a giant dove of peace.

Although the Prime Minister wants the UN and the EU to play a significant role in Iraq’s postwar reconstruction, and is determined to repair relations with Germany and France, his aides said he was not yet ready to be photographed proffering olive branches to erstwhile allies.

Washington’s rival effort to uncover Saddam’s weapons of mass destruction, a political imperative for the US and Britain, was sharply criticised by Dr Blix, whose inspectors were pulled out of Iraq shortly before the war began on March 20. He said that Washington should allow his team back into Iraq to look for banned weapons.

“The alliance arrived as liberator and occupier and that can have its disadvantages. If their experts actually find weapons of mass destruction, their veracity could be doubted,” Dr Blix said.

Referring to the surrender in Baghdad six days ago of Lieutenant-General Amer Hammoudi al-Saadi, Saddam’s top scientific adviser, Dr Blix said: “On surrender, he did say on television, to the whole world, that there are no weapons of mass destruction and that time would bear him out. I don’t see why he should have any reason to lie at this stage.” He added: “We have never claimed that Iraq had weapons of mass destruction, although we could not rule it out. Now we will see if London and Washington were right.”

Donald Rumsfeld, the US Defence Secretary, said yesterday: “Inspectors didn’t find anything and I doubt we will. What we will do is find the people who’ll tell us.”

Hopes for a breakthrough increased after the capture in Baghdad of Barzan Ibrahim Hasan al-Tikriti, a half-brother of Saddam. US Central Command said he had “extensive knowledge of the regime’s workings”.

Describing the intelligence on Saddam’s weapons programmes given to his inspectors by Washington and London as “pretty pathetic”, Dr Blix also challenged the US to present proof “very quickly” of its allegation that Syria had chemical weapons. Damascus yesterday said it would not allow inspectors on its soil.

Dr Blix will brief the Security Council next week on his preparedness to send a UN inspection team to Baghdad, a move that raises the possibility of a collision of rival inspection teams. A US official said: “We see no immediate for Unmovic (the UN Monitoring, Verification and Inspection Commission). Nor are we convinced that Blix is the right person to lead any effort in Iraq.”

Mr Blair told Parliament last week that “plainly it would be a good idea from every perspective” to make sure there was “some sort of objective verification” of any weapons find.

The US says it has been successful in recruiting between 30 and 40 former UN inspectors, many from the UN Special Commission, Unmovic’s predecessor, to form part of the Iraq Survey Group.

“It’s going to be a much more muscular organisation,” one defence official said. But some civilian experts contacted by the Pentagon to join the group are critical of the effort. One told The Times: “This seems to have been something slung together at the last minute with a few hand-picked people.”

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