David Cameron, Ed Miliband and every politician in Britain should be seeking psychiatric help, according to Alastair Campbell.

The former Downing Street spin doctor said consulting mental health professionals would improve how they dealt with stress and make them better leaders.

Mr Campbell also revealed that he urged Tony Blair and Gordon Brown to seek couples counselling when their working relationship disintegrated in government - but the prime minister rejected the idea.

The detail features in the Labour stalwart's latest book, Winners and How They Succeed, which is being serialised in the Sunday Times.

In it he argues that modern politicians are less effective leaders than senior figures in sport and business, where psychologists are routinely employed to improve performance.

"If you look at the best of elite sport, it does stuff better than the best of business, and the best of business does it better than the best of politics," Mr Campbell told the newspaper.

"Sport is predominantly a physical activity, and yet hardly any of these top sports guys go without proper psychological support. And yet politics, which is primarily intellectual, mental, psychological - most of them don't have any psychological support at all."

Mr Campbell said politicians were afraid of headlines like "Cameron has a shrink".

But the spin doctor said he hired Andy McCann, a mental skills coach to the Wales rugby team, to help him prepare for his appearance at the Chilcot inquiry into the Iraq War.

Campbell said New Labour finally lost power because Blair and Brown failed to pull together. "We didn't do so well on teamship, and I think if we had we'd still be there," he said.

He said he offered Mr Blair the services of the psychiatrist who was helping him battle depression in the run-up to the 2005 election, when the then-prime minister was under pressure from Mr Brown to announce when he would stand down.

Mr Blair replied: "I am prepared to think out of the box. But not that far."

Mr Campbell said current Labour and Tory frontbenchers lack the necessary determination to win.

"Can the Cabinet or shadow cabinet really say that they are waking up every day ... putting in the work and effort needed? None of the UK main parties communicate that sense of absolute focus and determination," he said.

Mr Campbell criticised Labour's decision to oppose the bombing of Syria in August 2013, because "what has followed is in some ways even worse".

But he said Miliband had shown "leadership". "Ed does big, bold things," he said. "The circumstances in which Ed became leader, that was a test of mettle on lots of levels."

While complaining that Labour should be "battering" the Tories, Mr Campbell hit out at "noises off" from Blairites such as Alan Milburn and John Hutton who have questioned the party's direction.

"I've said what I've said about the economy, but there is a time and a place. Where we are now in the electoral cycle, across the party everybody's got to get out and fight."