Tory leader tells Brown to repeat 'with a straight face' his denial that he had allowed staff to brief against the chancellor

Gordon Brown today denied that he and the chancellor, Alistair Darling, were "at war with each other" after being repeatedly taunted by David Cameron in heated Commons exchanges.

The Tory leader challenged Brown during prime minister's questions to repeat "with a straight face" his denial earlier today that he had allowed staff to brief against Darling.

Cameron seized on an accusation levelled by the chancellor on television last night that "the forces of hell" had been unleashed against him after he predicted the recession would be the worst for 60 years.

Questioned about the claims, Brown told GMTV this morning: "I would never instruct anybody to do anything other than support my chancellor." He added: "I was never part of anything to do with this."

Repeating the quotes in the Commons, Cameron said: "Try and stand up and say with a straight face and say it's true."

Brown replied, pointing at Cameron: "It's not only correct, but this is the nearest he's ever got to talking about the economy in the last few months."

Cameron then asked Brown to explain why he and the chancellor were "at war with each other" six weeks before an election, and at the end of a long recession.

The Tory leader, who joked that if Brown sat any closer to Darling on the Commons bench "they would start kissing", repeated allegations that Brown's former spin doctor, Damian McBride, "spread poison" about Darling.

As the Speaker, John Bercow, threatened to suspend the noisy sitting if MPs did not calm down, Brown said this had not happened. "I would rather be defending my chancellor than be in your position of having to defend your shadow chancellor," he told Cameron.

In his GMTV interview earlier today, the prime minister sought to portray his relationship with Darling as close and warm. "Alistair has been a friend of mine for 20 years," said Brown. "We have worked together. Our families know each other. We have worked together all this time and we have huge mutual respect for each other. I think he would confirm that."

Brown denied being a bully but admitted he could be viewed as "demanding" and a "hard task-master" who sometimes got angry and impatient. He said the day-to-day pressures of being prime minister were not for a "shrinking violet".

"I get angry sometimes – doesn't everybody? I get impatient. I am driven to do the things. When I came into the job, I said, 'Look, I will try my utmost,' and I challenge people, I ask them to do the best they can," Brown said.

"Actually, we work in an open-plan office; we are a sort of family in Downing Street and like every family there are issues that come from time to time, but we have a got a great working environment and we get things done."

He added: "In my job you have got to get things done, you have got to push people, you have got to challenge people. You don't solve a world recession by being a shrinking violet."

Darling spoke out last night when asked about Downing Street's reaction to a Guardian interview in August 2008 in which he said the world was facing "arguably the worst" economic downturn in 60 years. "I remember the weekend after we came back and I'd done this interview and the forces of hell were unleashed," the chancellor told Sky News.

Asked by the interviewer whether he meant No 10, Darling replied: "Not just them; the Tories as well."

He agreed with the interviewer's assertion that two key Brown allies – the former spin doctors Damian McBride and Charlie Whelan – had led the briefings against him. "Of course there were people saying things, but frankly my best answer for them is the fact that I'm still here, one of them is not," Darling said in a reference to McBride, who resigned last year.

Today Whelan declined to comment on the affair. McBride denied briefing against Darling.

An aide to Darling today claimed that the chancellor had not intended to criticise Brown when he gave his interview to Sky. "Alistair has never, publicly or privately, said that Gordon Brown was briefing against him," she said.

She also said that Darling had not accused Brown of instructing others to brief against him.

Downing Street has been fighting since the weekend to deny that Brown has bullied staff, after Andrew Rawnsley, the Observer's chief political commentator, claimed in a new book that the prime minister had been warned about his conduct. Citing Downing Street's furious reaction to Darling's 2008 Guardian interview, Rawnsley claimed that McBride resorted to "spreading poison" about Darling.

In his book, Rawnsley quotes Darling's wife, Maggie, as saying: "The fucking cunts are trying to stitch up Alistair!" Darling said last night that he could not remember his wife using such language.

Darling's confirmation that some of Brown's key allies had briefed against him will complicate Downing Street's attempts to rubbish the Rawnsley book. Sir Gus O'Donnell, the cabinet secretary, has denied Rawnsley's claim that he warned Brown about his conduct.

Speaking on BBC2's Newsnight on Monday, Rawnsley said: "What they have not denied on behalf of the cabinet secretary is that he had a conversation with the prime minister about his behaviour ... One person's idea of a verbal warning could be another person's private word."

Today it emerged that Rawnsley had dinner with Jeremy Heywood, the permanent secretary at No 10, in September last year. Heywood declared the dinner under civil service rules saying hospitality has to be registered.

In his interview this morning Brown said that his staff showed him "huge loyalty" and that they worked together as a team.

"I don't say it is not a difficult environment because you are challenged every day to make a decision."

Asked whether he was prepared to sue Rawnsley for libel over the allegations in his book, Brown said: "You could, you could, but you could spend all your time with legal actions."

Asked if it would leave a "stain on his character", Brown replied: "I don't think it will, because I have answered the questions and I am saying: 'Look, I do get impatient, sometimes you get angry, sometimes you have to do things that are very, very challenging.'"

Brown also said that he was not like Winston Churchill, who had "battered" a cabinet when he was at the Ministry of Defence.

Brown said: "We still have got the mark of it there. I am not like that. But the thing is that you have got to get things done and you are pushing people all the time.

"We have had a recession and there are many people in jobs, many people who are still in their homes, many businesses that are still going because we had to intervene and take the action."