The former UN chief weapons inspector Hans Blix has said it would be "a serious matter" if weapons of mass destruction are not found in Iraq.

He added that he thought the British and American Governments may have read intelligence a certain way because they wanted a war.

Speaking to BBC One's Panorama programme, Dr Blix added his voice to the controversy surrounding Iraq's weapons of mass destruction.

He said that the public had repeatedly been told that these weapons could be "an imminent danger."

However, no weapons of mass destruction have been found, and this week senior UK Government sources said that they no longer believe that any will be found in Iraq.

Now Dr Blix says it is vital that UK Prime Minister Tony Blair finds evidence to back up his reasons for going to war.

He told Panorama: "The main justification which we were told, and the American people were told, and United Nations were told, was weapons of mass destruction.

Genuine belief

Tony Blair has stood by claims of weapons of mass destruction in Iraq

"Therefore I think that they ought to be able to rest it on that case, and if that basis sort of crumbles, or becomes shaky at any rate, well I think that's a serious matter."

Dr Blix, who retired from his job as the head of the UN weapons inspectorate at the end of June, was also asked if he thought intelligence was read accordingly because the UK and US wanted the war to go ahead.

"I think there was an element of that," he said.

He says he is concerned that the analysis of the evidence had not been "sufficiently critical" before the war.

But Dr Blix, who is now living back in his native Sweden, says he thinks the UK prime minister is genuine in his belief that there was a threat.

He said: "I had several conversations with Tony Blair and my definite impression was that he was convinced, subjectively convinced, that they had weapons of mass destruction."

Dr Blix was interviewed for Panorama: What happened next, which will be broadcast on BBC One at 2215BST on Sunday, 13 July.