3,900 knives seized by police in stop and search operation

The weapons were recovered in a series of hard-hitting operations which included carrying out more than 180,000 stop and searches of young people on the streets in the last eight months.

Senior officers say they believe they are using the right tactics, citing a 13 per cent fall in overall knife crime in the last 10 months.

However, the figures come just days after it emerged that the total number of knife-related murders in London this year jumped to 86 - a rise of a quarter on the figure for 2007.

Scotland Yard launched Operation Blunt 2 in May in response to a series of teenage murders. A total of 28 young people were murdered this year - a record number - but police hope that the crackdown on knives has curbed the rate of killings.

The last teenage murder took place on 8 November when 19-year-old Nabeer Bakurally was stabbed through the heart in Ilford.

Police say they have now recovered 3,900 knives and made more than 6,465 arrests.

Many of the knives have been recovered after police began doing "weapon sweeps" of local estates and found them hidden so they could be collected for use in gang fights.

The use of stop and search has been a key element of the operation despite fears that it could alienate sections of the youth population.

In an effort to reduce the impact of the searches, police have employed dozens of youths from deprived areas to advise officers at special workshops.

They are advising police on slang used by children as well as ways of being as inoffensive as possible in approaching people to search for weapons.

Police are also deploying metal detecting arches at bus and train stations and carrying out random checks at nightclubs in a Christmas and new year campaign against weapons.

The police operation has been backed by Mayor Boris Johnson, who has also announced a new youth strategy to tackle the roots of teenage criminality.

This includes providing more support to first-time offenders, fining parents of regular truants and setting up scholarships for disadvantaged children.

Detective Chief Superintendent Julian Worker said police believed the tactics were proving effective and police were planning a new series of knife checks at transport hubs to coincide with the return to school in January.

He said: "This is about breaking the culture of carrying knives among young people. Everyone has a part to play in that as well as the police.

"There is peer pressure and parents also have a responsibility. We need to stigmatise those people that carry knives."

In another initiative run by the charity Crimestoppers, school children are being urged to inform on fellow pupils who carry knives by texting the information anonymously to a special number.The breakdown of figures on teenage murders this year shows that there were 22 fatal stabbings and three fatal shootings, compared with 16 stabbings and nine shootings the previous year.

The remaining murders involved beatings where victims died from head injuries.