Gordon Brown's claim that an inquiry into the war in Iraq would be a "distraction" for Britain's troops on the ground has been repudiated by some of the country's former defence chiefs.

The Prime Minister said an inquiry should take place when the soldiers' "work is over", although ministers have denied that means when the last British soldier has left Iraq.

But a number of Britain's former leading defence figures have rejected the Prime Minister's warnings that to hold an investigation now would undermine the troops, and supported the demands for an urgent inquiry into the war. Among them is Field Marshal Lord Bramall, who commanded British forces during the Falklands War.

Download the new Independent Premium app Sharing the full story, not just the headlines

The Government defeated demands in the Commons by Liberal Democrats and Conservative MPs for an inquiry this week, although 12 Labour MPs rebelled.

Gordon Brown has promised an inquiry but said now was not the time. Lord Bramall accused the Prime Minister of delaying it for political reasons.

"I don't think having an inquiry now would be a distraction. I think it is such a political hot potato the Government is not going to want it before the next election," he said. "There are two issues which people want to know about – why was there no planning for the aftermath of the war and how did we get involved in the first place."

Lord Bramall, who was opposed to the war, said that the Prime Minister failed properly to consult the chiefs of staff or his cabinet colleagues before supporting President George Bush in going to war.

"We now know that the prime minister didn't consult anybody in his own Cabinet before we were committed to war, and the Americans decided it as a reflex action to 9/11."

Lord Craig of Radley, the former air marshal of the RAF, backed Lord Bramall's demand for an immediate inquiry.

"I think it is very timely to have an inquiry before memories fade," said Lord Craig. "The fact that there remain some British troops still in Iraq – they are in an 'overwatch' role and not actively engaged – should not delay it.

Inside Politics newsletter The latest news on Brexit, politics and beyond direct to your inbox Enter your email address Continue Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid Email already exists. Log in to update your newsletter preferences Register with your social account or click here to log in I would like to receive updates on politics every morning by email Update newsletter preferences

Lord Craig said he did not agree that an inquiry would prove a distraction. "I would personally like to see an inquiry because I think there are lessons to be learnt. I do not think that it would be a distraction at all. The issue is about how we got involved in the war."

He said any inquiry would not involve those now on the ground in Iraq. "It would involve those who were involved in the decision at the most senior levels. The issue is how did we get into it, and what arrangements were made for after the invasion?"

The former head of the RAF rejected the assertion by Jack Straw, the Justice Secretary, that an inquiry now would affect soldiers "psychologically".

"I don't think an inquiry would have any psychological impact on the troops," said Lord Craig.

General Sir Mike Jackson also supported an inquiry. He said: "As I said in my book, it is a political decision at the end of the day but in the long run it would probably be a good thing."

The Prime Minister's official spokesman yesterday said that Mr Brown remained of the view that an inquiry now would be a "distraction", in spite of the calls by the defence chiefs.

In a letter to the Fabian Society, which had earlier asked him to hold a public inquiry, Mr Brown wrote: "There will come a time when it is appropriate to hold an inquiry. But while the whole effort of the Government and the armed forces is directed towards supporting the people and government of Iraq as they forge a future based on reconciliation, democracy, prosperity and security, we believe that is not now."