By Charles MaggsFollow @charlesmaggs

Peter Mandelson has admitted Tony Blair made a mistake invading Iraq, as he did not foresee the prolonged violence that was to engulf the country.

In an interview with Esquire magazine, the former king of spin said Blair had been expecting a "short, sharp success" rather than eight years of sectarian killing.

"He expected it, obviously, not to be a walk in the park but to be a short, sweet success with the downfall of Saddam," he said.

"But it didn't turn out like that, which was more the Americans' fault than his, but I think he should have gone into it with his eyes wider open."

Although Mandelson was not a part of the government at the time of the invasion, he remained a towering figure within New Labour.

He goes onto confess he had aspirations to become foreign minister, although this would have been politically difficult given that he was forced to resign from the Cabinet three times before becoming European commissioner in 2004.

He was later appointed business secretary by Gordon Brown in 2009 and was a key part of Labour's election team in 2010.