The United States, Britain and Libya on Saturday pledged their full support for efforts by their investigators to bring those behind the 1988 Lockerbie airliner bombing to justice.
In a joint statement on the 25th anniversary of the downing of Pan Am flight 103 in which 270 people were killed, the three governments said were determined to unearth the truth behind the deadliest such attack in Britain.
"We want all those responsible for this most brutal act of terrorism brought to justice, and to understand why it was committed," they said in the statement, issued by Britain's Foreign Office.
"We are committed to cooperate fully in order to reveal the full facts of the case," the statement said. "We will all provide full support to the investigation team to enable them to complete their enquiries successfully."
The Tripoli government, trying to establish its authority after NATO air power helped rebels overthrow Muammar Gadhafi in 2011, wants to show its willingness to help its Western partners clear up the many unanswered questions about Lockerbie, an attack which for years kept Libya an international pariah.
British Prime Minister David Cameron praised the "fortitude and resilience" of those affected by the bombing, as anniversary services were held in Britain and the United States.
Most of the victims of the explosion over Lockerbie in Scotland were Americans on their way home from Europe for Christmas.
Eleven people died on the ground as the New York-bound jet plunged from the sky after a bomb exploded in its hold some 38 minutes after leaving London's Heathrow airport.
Libyan intelligence officer Abdel Basset al-Megrahi was the only person ever convicted over the attack.
He was found guilty, in association with others, of the bombing in 2001 but released from jail on compassionate grounds eight years later amid huge controversy both in Britain and America. He died of cancer last year.
Megrahi always protested his innocence and his family is considering lodging another appeal to clear his name.
In 2003, Gadhafi accepted Libya's responsibility for the bombing and paid compensation to the victims' families but did not admit personally ordering the attack.
After his overthrow and killing in 2011, two Libyan prosecutors were appointed to work with Scottish and U.S. investigators trying to identify the other perpetrators.
One man they want to question is Abdullah Senussi, Gaddafi's former intelligence chief, who is awaiting trial in Libya for war crimes allegedly committed during the 2011 uprising.
Earlier this week, Libyan Justice Minister Salah Marghani said he planned to allow the prosecutors to talk to Senussi.
"What we are working on is finalizing the arrangements for this as much as obtaining the evidence that's available with the UK and US authorities," he told ITV news.
"We all need to know the facts," he said.