The pair were also acquitted of manslaughter and assault with intent to rob.

The 16-year-olds, who cannot be named for legal reasons, hugged their mother with relief on hearing the verdict at the Old Bailey.

Damilola bled to death in the stairwell of a block of flats on the North Peckham estate, London, in November 2000.

Mr and Mrs Taylor feel that the court proceedings have brought them no nearer to these burning questions that continue to torment them

Neil O'May Taylor family solicitor

Two other defendants, aged 14 and 17, had previously been cleared on the direction of the judge. All four youths had denied the charges.

Outside the court, defence solicitor Chris Hartnell accused the police of "political opportunism" and said there had been no worthy evidence against the four.

"The police... simply felt they had to produce someone and produce someone they did - it was the usual suspects and people they at first thought of."

But the Crown Prosecution Service (CPS) said they had examined all the evidence carefully.

A CPS spokesman said: "We realised that it would be a difficult case to prosecute because of the lack of eyewitnesses who came forward.

"However we considered that there was enough evidence to put before the court."

Downing Street said if there were issues to arise from the trial, they would be addressed.

Huge investigation

On hearing Thursday's verdict, the brothers burst into tears but the Taylor family showed no emotion.

The family solicitor Neil O'May said: "Their struggle to understand what went on continues.

"They know their son was murdered. They don't know who did it or why it happened but they know he died at the hands of others."

Asked if they would consider a civil action, he said: "They need time to come to terms with the verdict."

DS Shepherd: Case remains open

The investigation and trial are estimated to have cost �10m.

Detective Superintendent Trevor Shepherd, at a Scotland Yard press conference, maintained there had been enough evidence to prosecute.

He said the case remained open, although there were no fresh leads.

The detective, who apologised in person to the Taylors after the verdict, said the police received little co-operation from teenagers on the estate.

He said they had been hampered by the lack of witnesses and a "hostile" gang culture, but added: "Friendships and loyalties can change."

Mr Taylor showed no emotion when the verdict came

The police ended up relying for much of their case on the one girl who did come forward, a 14-year-old named in court only as Bromley.

But her evidence was thrown out of court after the judge said she was "an accomplished liar", and criticised police tactics in dealing with her, saying she could have been induced by rewards.

London Mayor Ken Livingstone said: "The Metropolitan Police Authority should conduct its own investigation into the conduct of the case to establish what went wrong.

"Whatever the rights and wrongs of this case, the verdict means one thing - Damilola's killers are still at large."

'Not my children'

The two brothers have a history of minor convictions, and have faced more serious charges including assault, indecent assault and intimidation of witnesses.

Their mother told BBC News after the trial the police had "always had it in" for her sons because they had been in trouble for "small, petty sort of things".

But she said: "From day one I knew it couldn't have been my children, because... they've always looked out for the children on the estate. And I know in my heart that my children are not capable of hurting anyone".

The prosecution claimed Damilola died after being stabbed in the leg with a broken bottle.

But the defence argued his fatal wounds were the result of a fall on shattered glass.

Lawyers for the 17-year-old defendant who was cleared in February, said they were considering an action for malicious prosecution against the police.