The bloodstained items were taken from six men arrested at the scene of the murder during the Broadwater Farm riots in Tottenham, north London, in 1985, said the Daily Mail.

Advances in forensic science mean blood samples can be taken from the clothes and tested to see if they are compatible with PC Blakelock.

The estate at the height of the riots

The pattern of blood on the clothes will be analysed to assess whether any of the suspects could have carried out the killing. Police will also carry out a new search for fingerprint matches.

Scotland Yard would not confirm the reports but said officers would use whatever technology was available to them.

"We are of course fully aware of the advances in DNA testing. Officers investigating major crimes will use these techniques whenever appropriate," said a spokesman.

Officers are also asking for up to 50 others who were not involved in the killing, but who were at the scene and may have been witnesses, to come forward with information.

A review of the case, led by a senior detective, was announced earlier this year.

Quashed convictions

The 40-year-old officer was hacked to death on the council estate in October 1985 after he slipped and fell while trying to protect firemen who were dealing with a blaze started by rioters.

The killers have never been brought to justice. In 1987 three men - Winston Silcott, Mark Braithwaite and Engin Raghip - were convicted of PC Blakelock's murder, but the convictions were quashed on appeal.

The reported tests come after the Metropolitan Police last month agreed to pay Winston Silcott a �50,000 out-of-court settlement for malicious arrest and false imprisonment.

It is understood that the new avenue of inquiry came to light as police prepared their case against Silcott's civil claim.