Stephen Lawrence was stabbed to death while waiting for a bus

The Crown Prosecution Service made the decision after reviewing the five-year-long reinvestigation.

However, Mr Lawrence's family, who say that had Stephen been white his killers would have been convicted, have vowed to continue their campaign for justice.

Mr Lawrence, 18, was stabbed in April 1993 in a racially motivated attack in Eltham, south-east London.

In 1996, three men were acquitted of murder after an Old Bailey trial.

'False hope'

Stephen Lawrence's mother Doreen told BBC news she was "devastated" by the decision not to press new charges against the key suspects

"I have had to be fighting for everything that's happened so far.

"I've had to struggle all these years in the false hope that Stephen's killers would be caught and be put behind bars."

She has continued to claim race was an issue in the way the original investigation was carried out, saying "had Stephen been white they would have found his killers".

She added: "They've missed their opportunity and why did they miss the opportunity, those are the sort of questions that I want answers to."

Had Stephen been white they would have found his killers Doreen Lawrence Mother's anger Stephen Lawrence's legacy

The Lawrence family solicitor Imran Khan said it was possible the family would now consider a judicial review of the CPS's decision.

Home Secretary David Blunkett said: "The tragedy of the Lawrence story is not only the horror of Stephen Lawrence's brutal and senseless murder, but the failure to get the evidence needed to bring a case to prosecute."

The CPS pointed out that although the reinvestigation did produce a new witness, the evidence did not provide a sufficiently reliable identification.

No credible evidence

It added there was no credible forensic evidence and any alleged confessions proved to be hearsay and not admissible.

Sir Ian Blair, deputy commissioner of the Metropolitan Police, said the decision was a "grave disappointment".

"We have mounted a very meticulous investigation using all sorts of new and inventive methods to attempt to bring the killers of Stephen to justice.

"At this stage that has not been sufficient but no case is ever closed.

We all need to reflect on this dreadful murder and recognise the profound effect it has had on our national consciousness Ken Macdonald QC, director of Public Prosecutions CPS statement in full

"The legacy of Stephen is a completely different Metropolitan Police Service, one which has learnt so many lessons in how to investigate racist crimes of this type."

Soon after Stephen Lawrence was killed, five men - Neil Acourt and his brother Jamie, David Norris, Gary Dobson and Luke Knight - were arrested.

But proceedings against Neil Acourt and Mr Knight were later discontinued by the CPS following a meeting with the senior investigating officer.

Then parents Doreen and Neville Lawrence took out a private prosecution against the five men, but the case against Jamie Acourt and Mr Norris was dropped at an early stage.

Neil Acourt, Mr Knight and Mr Dobson eventually stood trial for murder.

Charges dropped

A week after the start of proceedings, the jury was ordered to find the defendants not guilty after the judge decided the evidence of Duwayne Brooks, who was with the 18-year-old at the time of the attack, was unreliable.

In February 1997 an inquest into Mr Lawrence's death ended when a jury decided the teenager had been "unlawfully killed in a completely unprovoked racist attack by five white youths".

An official report into the initial murder inquiry branded the Metropolitan Police force "institutionally racist".

Metropolitan Police Commissioner Sir John Stevens once said during an interview that he knew who killed Mr Lawrence.