WPc Fletcher was policing a small crowd demonstrating against Libyan leader Muammar Gaddafi when she was hit by a bullet.

Witnesses said at the time a man appeared at the window of the embassy and suddenly opened fire. Police believe that the man could have been firing at the demonstrators.

No one charged

On Wednesday the Libyan government accepted "general responsibility" for the killing and promised to cooperate with a police investigation.

No one has ever been charged with the murder of the 25-year-old policewoman. The occupants of the embassy at the time were escorted to Heathrow airport after an 11-day seige of the building and put on a plane back to Libya

Diplomatic relations with Libya were immediately broken off.

This combined with a further deterioration of the political climate between the two countries after Libya was held responsible for the bombing of a plane over Lockerbie, Scotland, made an investigation into the WPc's death impossible.

But with the improvement in the diplomatic climate, detectives expect to take written statements from Libyan officials who were in the embassy at the time of the shooting.

Request for assistance

A joint statement following weeks of negotiation between Britain and Libya stated that Libya would cooperate with detectives from the Metropolitan Police anti-terrorist branch.

Detectives will liaise with the Crown Prosecution Service to produce a letter detailing which lines of inquiry they want to persue. According to the force, the letter will be sent to the Libyans "asking for their assistance in the inquiry."

Senior diplomatic sources in London suggested that if any Libyans were charged with the killing, Libya would find it hard to resist the "logical demand for justice".

According to a report in the Daily Telegraph on Thursday, it is believed detectives have identified the likely floor and window the shot was fired from. They believe fingerprints taken from the embassy will pin-point who was on that floor at the time of the shooting.

The newspaper report says it is believed that police have produced an intelligence picture involving a number of men in the embassy at the time of the shooting.

But it is not yet clear whether officers would fly to Libya to persue their questioning, or whether Libyan officers would be expected to come to London.

Yvonne Fletcher: investigation into her death was almost impossible until now

The mother of WPc Fletcher has waited 15 years for a breakthrough that could help bring those responsible for her daughter's death to justice.

"No one can any longer cast doubt on what has happened. We hope that there can now be progress on identifying precisely who was responsible for Yvonne's death," said Queenie Fletcher.

"The path to full justice for Yvonne is now open."

Scotland Yard opened an investigation into the murder in 1997, after a television programme claimed the bullet that killled WPc Fletcher was fired from another building and could have been linked to a CIA plot to kill Col Gadaffi.