More than 500 teenage gang members are being targeted in a police operation to tackle half-term holiday street violence.

Scotland Yard said last night that it had amassed intelligence on children as young as 11 in an attempt to prevent an increase of youth crime during the school break.

Operation Kartel will focus on hotspots in South and East London where teenage knife and gun crime have been running at alarming levels.

Last year 27 teenagers were murdered in London. So far in 2008 four teenagers have been killed. Sir Ian Blair, the Metropolitan Police Commissioner, has described the death toll as unacceptable.

There have been similar surges in youth violence in other cities, including the murders of Rhys Jones in Liver-pool and Jessie James in Manchester.

The half-term operation will step up police patrols on the streets and on trains and buses, and 30 mobile search arches will be in use at transport hubs. In addition to searching individuals, police will conduct “weapons sweeps” to locate caches of knives and other weaponry hidden on housing estates or close to areas where gangs might congregate.

Superintendent David Chinchen, from the Metropolitan Police, said that officers in the capital were “raising our game” to deal with the threat of violence at a time when many youths were out of school and on the streets. “We are focusing on a number of individuals involved in serious violence and who are ignoring all the warnings about carrying weapons,” Mr Chinchen said. “Some of them run around in what they like to call gangs. But our focus is on individuals, not on particular gangs or groups. We are ramping up a programme of activity to deal with a minority of young people who are using violence on the streets.”

Mr Chinchen said that the use of firearms had declined since a spate of teenage gun murders in London last year, but there was increasing concern about knife attacks. He added: “A lot of the violence is not over signficant issues – it is minor disputes that esca-late and turn into serious incidents.”

In addition to action against known individuals, Mr Chinchen said that officers would visit the parents of children identified as being on the fringe of gang activity and at risk of either becoming involved or being hurt.

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