A police unit set up to tackle gun murders in black communities will now no longer work on firearms deaths.
Last year, the Metropolitan Police changed the brief of Trident Gang Command so it no longer focused on black crime either.
All gun murders will be investigated by the Homicide and Serious Crime Command and Trident will focus on prevention.
A former adviser to the Met said it was rolling back the years and "saying black lives are cheap".
Operation Trident was set up in 1998 in response to shootings disproportionately affecting black people in London.
Since last year, the Trident unit's brief has been gang-related crime, especially shootings, regardless of race.
The Met said this had led to an "unhelpful" situation where murders were distinguished on the basis of the weapon used, when the same offenders could be involved in both knife and gun deaths.
Commander for Gangs and Organised Crime, Steve Rodhouse said he refuted the accusation of former Met adviser Claudia Webb, who helped launch Trident.
He said: "It is absolutely not the case in the eyes of the Met Police that black lives are cheap."
He said Trident was changing to meet the current need of the Met and all Londoners.
In 2011 there were 14 gun murders but since April 2012 there have been five, according to the Met.
Commander Steve Rodhouse also said: "This is not a cost-saving measure in any way."
The Met said 120 officers would be deployed into the Trident Gang Command which will still investigate non-fatal gang crime such as firearms trafficking and concentrate on preventing gun, gang and knife crime.
'Scared for children'
Ms Webb said it was a "fundamental ripping out of the engine of Trident" and the unit would now exist in name only.
Former Trident officer Chris Hobbs said that the "dilution" of Trident was a mistake but that the expertise should be retained under one command.
Donna Sinclair, from Options for Change, works in Lambeth, Southwark, Croydon and Wandsworth to help disengaged youths from poor backgrounds who can fall into gang crime.
She said in her experience Trident's community engagement had been "lacking" since the London riots in 2011.
She added: "If Trident's resourced adequately, fantastic. If it's not, I'm scared for our children and young people."
The decision to change Trident's remit was made last week, a spokeswoman said.
Operation Trident was set up in response to a string of so-called "black-on-black" shootings and murders in Lambeth and Brent.
Officers were finding the cases hard to investigate as fear of reprisals meant witnesses were afraid to come forward, and there was a general distrust of the police.
As the violence continued, the operation was extended to cover the whole of the capital a year later.