Tony Blair has said that the information was genuine

The US Secretary of State has said a claim to the United Nations that Iraq had mobile laboratories may not have been based on "solid" intelligence.

Labour MP Doug Henderson has said that American people have been misled and it appears that UK citizens have as well.

Mr Powell said the labs could be used to develop weapons of mass destruction.

The claim was made at a meeting of the United Nations Security Council in February 2003.

It did not persuade a majority of the council's members to back the US case for war but it did influence American public opinion.

Dreadful error

The US Secretary of State said he would be taking up the issue with the Central Intelligence Agency.

Mr Powell's admission has prompted some UK critics of the war to wonder whether similar claims made by the prime minister and the government in the run up to war came from the same source.

The cat is out of the bag, now we have every reason to believe that the information does not stand up Sir Menzies Campbell, Liberal Democrats

Mr Henderson, a former defence and Foreign Office Minister, has said that the record had to be put straight on faulty intelligence.

"Those who are responsible should apologise to those who have lost loved ones because of this dreadful error of judgment and a statement should be made to Parliament," he said.

The Liberal Democrat foreign affairs spokesman Sir Menzies Campbell said the admission was further evidence of the intelligence case for war "unravelling".

"The cat is out of the bag. The certainty with which Colin Powell lectured the Security Council of the United Nations was overwhelming.

"Now we have every reason to believe that the information upon which he was relying does not stand up," Mr Campbell said.

Butler Inquiry

In the UK a parliamentary inquiry has been probing intelligence on Iraq's weapons of mass destruction (WMD), but last month the Conservative Party withdrew its support from the committee which is being led by Lord Butler.

Tony Blair called the inquiry following mounting pressure caused by the failure to find WMD stockpiles and the US decision to hold a similar investigation.

The Butler Inquiry has been set up to investigate intelligence

More controversially was the admission by the former US chief weapons inspector in Iraq, David Kay, who said he does not know whether Iraq ever had a mobile weapons programme.

Foreign Office minister Mike O'Brien has insisted that all intelligence issues come under the remit of the Butler Inquiry.

"That has got the objective of looking at the intelligence received behind the issue of the WMD allegations in relation to Iraq. So that is now being investigated.

"When Lord Butler reports we will know more about the way in which that intelligence was collected," he said.

In September 2002 the UK government's dossier on Iraqi WMD said that the Saddam Hussein regime had developed mobile laboratories for military use, which supported previous reports about the mobile production of biological warfare agents.

"These would help Iraq conceal and protect biological agent production from military attack or UN inspection," it said.

Last January Tony Blair said he had no doubt in his mind that the intelligence was genuine.