Banker Bob Diamond has introduced what he calls 'the no-jerk rule' and has encouraged at least 40 executives at his firm to find jobs elsewhere.

The American-born chief executive of Barclays said he does not care how good people are at what they do, if they are not suitable, they will be asked to leave.

So far he claims dozens of executives have been shown the door after behaving like jerks or spending lavish amounts of money.

Mr Diamond also said if bankers act like 'Prima Donnas' or don't get along with their colleagues they can work elsehwere.

'You know what a jerk is when you see it,' he said. 'If we ever ignore the rule it always comes back to haunt us.'

The millionaire, who boasts high profits, big bonuses and an annual salary of £6.75 million said the 'greed is good' attitude of some bankers was 'a bit' of a jerk thing to do.

He also mentioned an incident which involved a Barclays investment banker wracking up a bill of £44,000 on wine at Michelin-starred restaurant Petrus.

'That was embarrassing. It was taking advantage - we have a responsibility to our colleauges and to have acted that way in a public place was inexcusable,' he told The Guardian newspaper.

Although he is known for flying easyJet instead of private jets and preferring to eat at Pizza Express instead of high brow restaurants, some might feel the comments are a bit rich coming from a man whose doorman is dressed in fur.

Peter Mandelson once called Mr Diamond the 'unacceptable face of banking' and he also provoked outrage last year when he said the time for remorse and apology from bankers was over.

But Mr Diamond is now calling for bankers to try and become better people.

'I don't think niceness is ever a sign of weakness. When people are mean it's usually a defence mechanism.

'Everyone gets stressed from time to time but no one should ever not be nice.'