Prosecutors say police investigating the 1984 killing of Pc Yvonne Fletcher need to visit Libya after a new suspect in the case emerged.
Pc Fletcher, 25, was shot dead while policing a protest against the Gaddafi regime at London's Libyan embassy.
The Daily Telegraph says a report for the Crown Prosecution Service includes a witness account claiming the shooter was Abdulmagid Salah Ameri.
The Foreign Office has said concluding the investigation is a "priority".
It confirmed it stood "ready to help" Scotland Yard detectives visit Libya as soon as conditions allowed.
BBC home affairs correspondent Tom Symonds says the Crown Prosecution Service believes pursuing the case will require detectives to conduct interviews in Libya itself, something which could become easier once the situation in the country has stablised.
Rebel fighters opposed to Col Muammar Gaddafi's 42-year regime have been fighting loyalist troops since an uprising in February, and say they now have almost complete control of the capital Tripoli.
Britain has recognised the rebels' National Transitional Council as the sole governmental authority for Libya.
No-one has ever been charged with Pc Fletcher's murder. While the shots that killed her were fired from inside the embassy, the Libyan staff claimed diplomatic immunity and were deported.
According to the Telegraph, a witness statement given by painter and decorator David Robertson to an independent review of the evidence by a Canadian prosecutor, claims to have seen a man shooting from the embassy.
The newspaper says junior diplomat Abdulmagid Salah Ameri was identified as the suspected gunman from television footage of staff leaving the embassy at the end of an 11-day siege that followed the shooting.
It quotes the CPS report as saying: "The man was holding the stock of the gun in his right hand, while his left hand was near the trigger area, as if he was about to fire. There were other men with him, with one to his left and at least two others standing behind him.
"Mr Robertson made a comment to someone to his left about the gun and, as he did so, he heard the gun being fired from the direction of the bureau, a 'rapid rat-a-tat-tat' lasting for two or three seconds."
A spokesman for the Metropolitan Police would not comment on the Telegraph's naming of the alleged suspect, but said: "The murder investigation has always remained open and the MPS remains committed to identifying those people responsible for killing WPc Yvonne Fletcher," he said.
"Detectives remain in regular contact with WPc Fletcher's family and update them on developments."
A Foreign Office spokesman said: "Helping the Metropolitan Police Service conclude the investigation that started in 1984 into the killing of WPc Yvonne Fletcher is a priority for this government.
"It will be an important element in the UK's relations with the new government of Libya.
"We are in contact with the Met and stand ready to assist them in returning to Tripoli when the conditions on the ground allow."