More than 500 of London's most dangerous gang members are in jail after a year-long crackdown, police figures show.

Launched in February 2012 at a cost of £60m, the Metropolitan Police's Trident Gang Crime Command has made more than 4,000 arrests.

There has also been a fall in the number of cases of youth violence with 1,500 fewer victims than a year earlier.

The number of victims of knife crime in London fell by 436 - around 28 percent - and there were 77 fewer shootings - a drop of 18 percent. There were six firearm murders in London in the past 12 months.

Originally set up to focus on gun crime and homicide within the black community, the command switched focus to tackle gang-related crime and associated violence and shootings across all backgrounds.

Scotland Yard said that 561 of the top 2,000 most harmful gang members were in jail - more than double the figure in March 2012.

Police seized 340 guns including one Kalashnikov assault rifle.

Trident-led investigations have resulted in jail sentences totalling 1,334 years, including 16 life sentences.

Det Chief Supt Dean Haydon, head of Trident Gang Crime Command, said: "This year we have seen some fantastic results in terms of enforcement. Tackling gang-related violence remains a key priority for the [Metropolitan Police] and we will continue to target and convict those who choose to carry weapons and cause harm in London's communities."

Cmdr Steve Rodhouse said: "When we launched the new command last year our aim was to drastically lower levels of serious youth violence, knife crime and gun crime in the capital, make the Met's response faster and to ensure we had the appropriate numbers of officers and staff focused on tackling gang crime. Our new approach is clearly working and we are now seeing reductions across all gang-related crime types."

Stephen Greenhalgh, deputy mayor for policing and crime, said: "The success of the Trident Command in its first year shows that real progress is being made. We are determined to enhance this good enforcement effort by the Met with effective new programmes that both prevent youngsters from joining gangs and divert youngsters from gangs."