Boris plans to strip young thugs of their Oyster cards

The Tory mayoral candidate pledged to bring in a scheme called "Payback London" which would encourage antisocial young people to view free travel as a privilege.

His plan is one of a series of measures to tackle crime in the capital - which he has pledged will be his number one priority should he win the mayoral election - to be unveiled later this week.

Mr Johnson told the BBC's Sunday AM programme: "We should take Oyster cards from the tiny minority that are abusing the privilege. If people knew they would systematically be deprived of it they would be much less willing to intimidate other passengers.

"If they want that privilege back - it has been given to 18-year-olds and under at the expense of lots of other people travelling on buses - then they should earn it back.

"They would have to do some kind of community service or voluntary service from graffiti removal, painting a community centre, whatever it happens to be. I think it would be a good way of connecting people with the privilege they're getting and making them value it."

Mr Johnson also pledged to introduce free travel for wounded troops in the capital.

He has called for more uniformed Police Community Support Officers and a trial of live CCTV on the buses to tackle anti-social young people.

However, a spokesman for Ken Livingstone's campaign said: "This shows how ill-informed Boris Johnson is - free travel cards are already confiscated for anti-social behaviour on buses.

"Anyone cautioned by the police or convicted of a criminal offence loses their card permanently, which is a very effective deterrent, whereas Boris Johnson's proposal would lessen this punishment."