One of the highest ranking officers in the Metropolitan Police told the inquiry into the way the killing was investigated that his force had "let down" the Lawrence family.

Assistant Commissioner Ian Johnston told Stephen's father, Neville Lawrence, he was "very, very sorry" for not bringing the killers to justice.

"Mr Lawrence, I wanted to say to you that I am truly sorry that we have let you down," he said.

"It has been a tragedy for you, you have lost a son and not seen his killers brought to justice."

Stephen, an 18-year-old A-level student, died after being stabbed near a bus stop in Eltham, south London, in 1993.

The fact his killers have escaped justice has led to accusations of racism and corruption in the Metropolitan Police.

The force has defended its actions at an on-going inquiry in Elephant and Castle, south London.

Mr Johnston will hope his apology will go some way to repairing relations between the police and the black community, which have been damaged by the case.

Speaking at the inquiry he said: "It has been a tragedy for the Metropolitan Police who have lost the confidence of a significant section of the community for the way we have handled the case.

"I can understand and explain some of what went wrong. I cannot and do not seek to justify it.

"We are determined to learn lessons from this. A great deal has changed and yet will change.

"We have tried over the last four years since the first investigation to show imagination and determination to prosecute Stephen's killers.

"I am very, very sorry and very, very sad that we have let you down.

"Looking back now I can see we could have, and should have done better.

"I deeply regret that we have not put his killers away.

"On behalf of myself and the commissioner, who specifically asked me to associate himself with these words, and the whole of the Metropolitan Police, I offer my sincere and deep apologies to you."

Mr Johnston, who became Assistant Commissioner in August 1994 more than a year after Stephen's death, added: "Finally I would like to add my own apologies for supporting the earlier investigation in ways in which it has now been shown that I was wrong.

"I hope the reasons for my support will be understood and I hope that eventually you will forgive me for that as well, Mr Lawrence."

But speaking later, Mr Johnston dismissed suggestions that police corruption was to blame for the failure to convict Stephen's killers.

He said: "My own personal view is that corruption had nothing whatsoever to do with it.