Detectives are poised to bring murder charges over the killing of PC Keith Blakelock during the Broadwater Farm riots, it has been reported.

The suspect, who was under 18 at the time of 1985 riots, will be prosecuted over his involvement in one of Britain's most notorious unsolved murders, the Sunday Telegraph has reported.

Sources told the newspaper that after reviewing the evidence against the man, two QCs agreed there is a realistic prospect of conviction - the hurdle which investigators must clear in order to win the backing of the Crown Prosecution Service.

Officially, Scotland Yard has insisted that no final decision had been made and that detectives were not yet ready to bring charges.

A spokesman said: "The re-investigation into the murder of PC Blakelock is ongoing.

"Regular consultation with the CPS has been taking place in relation to this case as is usual in all such investigations.

"We have not reached a decision regarding any charges against any individual."

The newspaper reported that sources believed the suspect was set to be charged within weeks.

Detectives' confidence was said to have been buoyed by the conviction in January of Gary Dobson and David Norris for the racist murder of Stephen Lawrence.

The officers believe that if such a long standing and legally complex case can be resolved then justice can also finally be secured for PC Blakelock.

PC Blakelock, 40, was attacked as he tried to protect firefighters who were tackling a supermarket blaze at the height of the riot on October 6, 1985.

After stumbling, the father of three was surrounded by a mob screaming "Kill the pig".

He was stabbed dozens of times and the machete-wielding killers then tried to decapitate him. A later trial heard the mob intended to parade the constable's head on a pole to taunt other officers.

Winston Silcott, Mark Braithwaite and Engin Raghip were convicted in March 1987 of PC Blakelock's murder but all three convictions were quashed four and a half years later, after forensic tests on pages of key interview records suggested they had been fabricated.

Silcott accepted £50,000 compensation from the Home Office but remained in prison for an unrelated murder and was released in 2003. None of the three men originally convicted is the suspect in the new case.

In 2003, Scotland Yard reopened the murder investigation after a review indicated there were possible new lines of inquiry.

It was revealed on the 25th anniversary of his murder, in October 2010, that 10 men had been arrested in London and Suffolk for questioning over the crime.

All were aged in their 40s or 50s and had lived in the Tottenham area at the time of the riot.

New forensic tests were carried out on PC Blakelock's flame-retardant overalls, which for years had been on show to criminologists and trainee police officers at Scotland Yard's "Black Museum".

The garment and more than a dozen murder weapons - several machetes and a kitchen knife found embedded up to the hilt in the constable's neck - were analysed using updated DNA techniques for the first time.

Evidence gathered by the new inquiry is also believed to include significant new witness statements.