The Prime Minister says he wants investigations to "get the full truth out" about "horrific" allegations, that police tried to smear the family of Stephen Lawrence.
An undercover police officer claims he was ordered to find information to discredit the family, Duwayne Brooks and campaigners.
He said it happened in 1993, just months after Stephen was murdered at a bus-stop in Eltham in an unprovoked racist attack.
Both the Home Secretary Theresa May and Mayor Boris Johnson spoke about possible criminal prosecutions of Met officers, if the claims prove to be true.
We have this report from our Senior Correspondent Ronke Phillips.
More top news
David Jones was responding to London's Fire Commissioner who said the term 'fireman' was outdated and should stop being used.
A report published by the Boundary Commission for England details plans to reduce the number of MPs by scrapping 50 constituencies.
Cressida Dick said that around £700m of savings have already been made.