Jack Straw today insisted that the Attorney General, Lord Goldsmith, plainly advised that the war with Iraq was legal.

The Foreign Secretary said that the advice given to the Cabinet on the legality of military action was "unequivocal", backing up an earlier statement by Tony Blair.

He refused to be drawn on a report in the Mail on Sunday yesterday that, in his detailed legal opinion, Lord Goldsmith had warned the war could breach international law in up to six ways.

"The Attorney General came to his view. He offered the view. It was unequivocal. The Prime Minister was right," Mr Straw told the BBC Radio 4 Today programme.

"There have been four separate inquiries into allegations which all go to the issue of the character of the conduct of the Prime Minister. None of those have said for a second that the Prime Minister lied or deceived anybody."

In heated exchanges with the BBC journalist John Humphrys, he declined to comment on the newspaper report.

"I am not confirming the contents of what is alleged to have been in a leaked document," he said.

Pressed as to whether that meant the public were entitled to assume that the Mail On Sunday report was accurate, Mr Straw replied: "They are not entitled to assume it is accurate either."

The report revived claims that Lord Goldsmith changed his advice between drawing up his original legal opinion and presenting his advice to the Cabinet a few days later on March 17, 2003, on the eve of the invasion.

Mr Straw said that he had presented a "summary" of that advice in a written answer to the House of Lords later that day.

"The Attorney General has repeated on many, many occasions that that view set out in the House of Lords on March 17 was indeed an accurate reflection of his opinion. That remains his view," he said.

He added: "Some of those who argue the legal advice was somehow wrong are basically trying to say the war was not justified.

"Where we have now got to is a far better Iraq and those who oppose a war - and I understand why they do that - need to understand that much good has come from it."

During the tetchy interview, Mr Humphrys accused Mr Straw of putting up "smokescreens" in order to avoid answering questions about Lord Goldsmith’s advice.

At one point Mr Straw told the presenter: "I have dealt with this. Keep your hair on."

The Foreign Secretary tried to refer back to UN Security Council resolution 1441 - which gave Saddam Hussein a final opportunity to disarm.

Mr Straw said that it had always been known that some lawyers felt that resolution 1441 was not adequate legal basis to invade Iraq, including some of the lawyers in the Foreign Office. "The fact that there was a disagreement among lawyers internationally and nationally was extremely well known. That was aired."

Mr Humphrys cut him off, saying: "No, that isn’t the issue." The journalist said that the issue was not the legality of the war, and accused Mr Straw of being "remarkably reluctant" to address the issue of the Attorney General's doubts, and whether Mr Blair lied about them.

"I'm not asking you that. I'm asking you why it was that the Attorney General drew up this document with a whole series of important caveats, and yet when the Prime Minister told us about the advice he had received he said it was unequivocal, and it manifestly was not unequivocal."

He did not give Mr Straw opportunity to respond to the question.

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