The decision to go to war based on that intelligence had been "right", said Peter Hain, who is Leader of the House of Commons and a key supporter of the prime minister.

Hain's vehemence comes despite growing signs that US President George W. Bush has accepted the possibility that evidence of chemical and biological weapons might never be found in Iraq.

Former chief US weapons hunter David Kay, who has stepped down as head of the Iraq Survey Group, said last week that pre-war intelligence about the weapons had been "all wrong".

On Sunday, the Washington Post reported that Bush has agreed to support an independent probe into any intelligence failures.

The stakes are particularly high for Blair, given that he invested a huge amount of his political credibility in seeking to persuade a sceptical British public that war was necessary because Iraq presented an immediate threat.

While inspectors "haven't found missiles in the middle of the Iraqi desert pointing at neighbouring countries", Hain said, the Iraq Survey Group had uncovered "a lot of evidence" of illegal weapons programmes.

The pre-war position was also clear, he said.

"I saw evidence that was categoric on Saddam possessing chemical and biological weapons of mass destruction," he told BBC television.

"I saw that intelligence evidence, so did the prime minister, so did other cabinet ministers. That informed our decision to go to topple him. I think we were right in doing so," he said.

WAR.WIRE