Libya's new rulers have promised to find and bring to trial the main surviving suspect in the 1984 murder of British policewoman Yvonne Fletcher, one of her former colleagues said Wednesday.

Retired police officer John Murray witnessed the shooting outside the Libyan embassy in London, as they policed a demonstration, and promised the dying Fletcher that he would find her killers.

The fatal shots were believed to have come from within the embassy, but all the staff were deported back to Libya under diplomatic immunity and no charges have ever been brought.

Following the overthrow of Moamer Kadhafi's regime, however, Murray said progress was finally being made in the case.

He travelled to Tripoli and met with Abdel Hafiz Ghoga, vice chairman of the National Transitional Council, who promised to find the chief surviving suspect, Matouk Mohammed Matouk.

"When he is detained he will be on trial in Libya for his crimes aginst the Libyan people, but more importantly for me he will also stand trial for Yvonne Fletcher's murder," Murray told the BBC from Libya.

"I've had a personal assurance from the vice-president himself that that will be the case."

Murray said he had been to Matouk's home in Tripoli but he had fled.

"We do believe he is still in Libya somewhere, the NTC are actively looking for him. He's got nowhere to hide, he's got nowhere to run. I have no doubt that very, very soon he will be captured and detained and stand trial," he said.

Ghoga said that extraditing Matouk to Britain to face trial "could be a possibility", but Murray said the important thing was that justice was done.

"Over the years I've had many many ups and downs. I've had hopes dashed. But with the new regime here it's really progressed things beyond my wildest dreams. It's the best chance I've ever had of obtaining justice for Yvonne."