The Mayor of London has taken greater responsibility of the police and vowed to target gang crime in the capital.

Boris Johnson today launched the Mayor’s Office for Policing and Crime, giving him unequivocal responsibility for the Met.

The new office replaces the Metropolitan Police Authority and means the Mayor holds the Met Commissioner to account.

As part of the shake up, it is understood Operation Trident, which deals with gun crime among black communities, will branch out into tackling gangs.

Specialist teams from the unit will head up a joint gangs taskforce that will tackle the sharp rise in youth violence.

Last month, Met Commissioner Bernard Hogan-Howe said gang crime was a "significant problem" in nearly half of London's boroughs.

He said: "If I was to pick out one thing that I want to do the most about its young people in gangs.

"It's not just about enforcement – we've got to talk about working with young people and getting them out of gangs."

Official figures show that 19 per cent of those arrested during the riots in London had been identified as gang members.

And there were 4,335 incidents of serious youth violence – stabbings, grievous bodily harm and other violence – in the six months from April to October 2011 compared with 3,921 in the same period the previous year – representing a 10.6 per cent increase.

A spokesman for the Met said the policy was still being planned.

He said: "The MPS is developing a strategy to tackle gang-related crime and serious youth violence in London.

"The new approach will enhance our anti-gang activities, improve co-ordination and tasking, and increase proactive operations, while making sure our skills and expertise in this area are used more consistently and effectively.”