Anti-racism campaigners have called on the London Mayor to scrap a controversial police gangs database.

A group including the director of Amnesty International UK Kate Allen and lawyer Imran Khan, known for representing the mother of murdered teenager Stephen Lawrence, claims that Scotland Yard's Gangs Matrix is

racist and the "wrong tool" to tackle the recent rise in violent crime.

In an open letter to Sadiq Khan on Tuesday, they said: "All of us strongly believe the Metropolitan Police's Gangs Matrix database is the wrong tool for the job. The Matrix is racially discriminatory: 78% of people on it are black, despite the fact that only 27% of those responsible for serious youth violence in London are black.

"In London, the term 'gang' has become heavily racialised - so much so that it is a significant hindrance to effective policy-making. To demonstrate the point, the Metropolitan Police's own figures show that only 5% of knife crime is related to 'gang' activity. To achieve the goal of a more peaceful capital city our response to violent crime must be evidence-based, not be tainted by institutional racism and mindful of human rights obligations."

The campaigners' letter called for an urgent meeting with Mr Khan and suggested that if the Matrix cannot be overhauled "it is time for it to be scrapped entirely".

In May, Amnesty published a report claiming that the Matrix stigmatised young black men - figures from July 2016 showed that 78% of those listed were black, whereas 13% of Londoners are black.

In terms of age, 80% of those on the database were between the ages of 12 and 24, and 15% were minors, the youngest of whom was 12 years old. Males accounted for 99%.

The murder of Stephen Lawrence and the botched original investigation into his death that was hampered by racial prejudice and suspected corruption were scrutinised by the Macpherson Inquiry, which concluded in 1999 that Scotland Yard was institutionally racist.

The letter to Mr Khan said: "No matter how grave the problem, we cannot afford to return to the pre-Macpherson era when discrimination in state agencies remained unchallenged and was allowed to ferment."

Being on the Matrix could affect access to services such as housing, education and the job centre, the Amnesty report found. Researchers heard some families were threatened with eviction if a young person did not change their behaviour, and one was sent an ultimatum more than a year after their son had died.

There were no "clear processes" for reviewing or updating the database, or challenging the inclusion of a name, and no definitive list of who is allowed access to the information, it said.

At the same time, data watchdog the Information Commissioner's Office announced that it was investigating the Matrix.

Deputy Mayor for Policing and Crime, Sophie Linden, said: "The Mayor has committed to reviewing the Gangs Matrix and this review should be completed before the end of the year."