The governments of Britain, US and Libya vowed yesterday to co-operate to reveal "the full facts" of the Lockerbie bombing which killed 270 people.

A joint statement by the three administrations, released on the 25th anniversary of the tragedy, said: "We want all those responsible for this most brutal act of terrorism brought to justice and to understand why it was committed.

"We are committed to co-operate fully in order to reveal the full facts of the case."

Scotland's top law officer Lord Advocate Frank Mulholland announced earlier that Libya appointed two prosecutors to work on the investigation into the bombing.

British and US investigators will visit Libya "in the near future" to discuss "all aspects of co-operation, including sharing of information and documents and access to witnesses."

The statement said: "We will all provide full support to the investigation team to enable them to complete their inquiries successfully."

Libyan Abdelbaset al-Megrahi was the only person convicted of the bombing. He was released from jail by the Scottish government on compassionate grounds after being diagnosed with prostate cancer and died last year protesting his innocence.

Mr Megrahi's family have said they plan to appeal against his conviction, while some of the British relatives of Lockerbie victims said they are also considering making another appeal.

Robert Mueller, the former head of the FBI, said he believes more people will be charged.

Senior politicians, including Scottish Secretary Alistair Carmichael and Deputy First Minister Nicola Sturgeon, joined friends and families of victims and former airline staff at Westminster Abbey on Saturday to remember the 270 people killed in the bombing of Pan Am flight 103 on December 21 1988.

Prayers were read by members of UK Families Flight 103, which was set up for loved ones of the victims to support each other and campaign for an independent inquiry.

Dr Jim Swire, whose daughter Flora died in the disaster, called on people to pray for the family of Mr Megrahi.

He said: "No philosophy can justify the slaughter of innocent people. In the West, we counter the threat of terrorism through intelligence gathering and the bringing to justice of those who hate.

"Please pray for all who do this desperate work for us."