Mr Straw warned his wife he might resign

Foreign Secretary Jack Straw is quoted in the Times as saying during the "very dark moments" in the run-up to the war he considered resigning with Tony Blair if rebellion by Labour MPs had been stronger.

And Home Secretary David Blunkett told the Guardian he had believed cabinet ministers close to Mr Blair would "go down with him".

Defence Secretary Geoff Hoon also warned his US counterpart Donald Rumsfeld that Britain might not be able to take part in the military campaign if the Commons vote went against the government.

I knew there was a point at which Tony would resign and I would resign as well Foreign Secretary Jack Straw

"The US came to understand it was about us gambling just about everything in getting this right," he told the Guardian.

The prime minister revealed last week he had told his family he might be forced to quit over Iraq.

In the event the government won the vote, although 139 Labour backbenchers had been among 217 MPs who backed a rebel amendment opposing the government's stance on Iraq.

The prime minister said he had told his officials and family to be prepared in case he had to resign.

Finely balanced vote

Mr Straw told the Guardian: "If we did not get the support we needed in the Commons - he [Mr Blair] would almost certainly go and I would go with him."

He said he had gone as far as telling his wife he might have to resign over the issue given the nature of the "projected voting figures."

"I knew there was a point at which Tony would resign and I would resign as well," he said.

Mr Blunkett reportedly told the same paper that everyone believed Mr Blair had put his premiership on the line.

"I thought it would be a hit on the government as a whole," he said.

Last week Mr Blair told the Sun he had even sat down to tell his children the vote would be "very difficult" and he feared he might be finished.