The Metropolitan Police has confirmed two detectives from the MPS Counter Terrorism Command have travelled to Libya, as part of the ongoing investigation into the murder of WPC Yvonne Fletcher.
They flew to Tripoli following a request from the Libyan authorities for officers to revisit.
The officers are due to meet Libyan officials to take forward preliminary discussions they held last month with a view to working jointly to identify who was responsible for WPC Fletcher's murder.
WPC Fletcher was policing a demonstration outside the Libyan Peoples' Bureau in St James's Square on 17 April 1984 when she was shot and fatally injured by a bullet fired from the building. Ten Libyan demonstrators were also injured in the incident.
Libya's former head of intelligence holds the key to solving the murder of policewoman Yvonne Fletcher, the Libyan prime minister has claimed.
Abdurrahim El-Keib, who has visited the spot where Wpc Fletcher was shot dead outside Libya's London embassy in 1984, told The Guardian Abdullah al-Senussi was the "black box" who would know who carried out the killing.
Senussi, one of Muammar Gaddafi's most senior henchmen, fled Libya last year and was arrested in Mauritania in March.
He is wanted by the International Criminal Court for crimes against humanity. He is also suspected of involvement in the Lockerbie bombing.
The family of Wpc Fletcher said they were pleased to hear that the Metropolitan Police had been given visas to continue their investigation in Libya.
Today we had a private meeting with Prime Minister Abdurrahim El-Keib and we look forward to the investigation progressing. We appreciate the support that we continue to receive from the police and the Foreign Office.
Libyan prime minister Abdurrahim El-Keib gave a talk today at Chatham House about Re-establishing The State. The politician, said his nation under Colonel Gaddafi "was a country where Libyans felt like aliens" and where people lived "as close as you can get to the poverty line".
Saying that citizens "lived in fear of the security apparatus", he spelt out his objectives for the country after elections are held on June 19 - for which 2.5 million people have registered to vote.
The premier said life had already changed in the short time since Gaddafi's downfall with freedom of the press, human rights and transparency as cornerstones of life. "These are special values that caused the revolution to take place," he said.