LONDON  - Britain, the United States and Libya issued a joint call Saturday for justice over the Lockerbie bombing as services were held to mark the 25th anniversary of the attack, which claimed 270 lives. The three governments gave their "deepest condolences" to relatives of those who died when Pan Am Flight 103 blew up over the Scottish town of Lockerbie on December 21, 1988, en route from London to New York.

All 259 people on board - most of them Americans heading home were killed as well as 11 people on the ground. "We want all those responsible for this most brutal act of terrorism brought to justice, and to understand why it was committed," the governments said in a statement.  "We are committed to cooperate fully in order to reveal the full facts of the case." Only one person has ever been convicted over the bombing - Libyan Abdelbaset Ali Mohmet al-Megrahi, who died last year still protesting his innocence.

Scotland's leader Alex Salmond was among the mourners laying wreaths on Sunday at Lockerbie's Dryfesdale Cemetery, which houses a memorial to the victims. "On this 25-year anniversary, and as the country prepares once more to relive the harrowing events of that terrible night, it is important that we remember that the pain and suffering of the families and friends of those who died has endured since that winter night in 1988," Salmond said.

US Attorney General Eric Holder and Scottish officials were set to attend a memorial service at Arlington National Cemetery just outside Washington, while Syracuse University in New York, which lost 35 students in the bombing, was also holding a remembrance ceremony. Mourners were also gathering at London's Westminster Abbey.

Prime Minister David Cameron paid tribute to the victims' families, saying their "fortitude and resilience" showed that terrorists would never win. "You have shown that terrorist acts cannot crush the human spirit. That is why terrorism will never prevail," he said in a statement.

Libya admitted responsibility for the bombing in 2003 and the regime of slain dictator Moamer Kadhafi eventually paid $2.7 billion in compensation to victims' families as part of a raft of measures aimed at a rapprochement with the West. Since the fall of the Kadhafi regime in 2011, British and US detectives have travelled to Libya to investigate whether other perpetrators could be identified.

"Over the last quarter of a century much attention has been focused on the perpetrators of the atrocity," Cameron said. "Today our thoughts turn to its victims and to those whose lives have been touched and changed by what happened at Lockerbie that night." The three governments said Saturday they would "all provide full support to the investigation team to enable them to complete their enquiries successfully". "We are striving to further deepen our cooperation and welcome the visit by UK and US investigators to Libya in the near future to discuss all aspects of that cooperation, including sharing of information and documents and access to witnesses," they said.

He added that the attack continued to forge a strong bond between Syracuse University and Lockerbie through a scholarship programme that sends two students from the Scottish town to New York every year. "This is the lasting and optimistic legacy bequeathed to future generations on behalf of those who lost their lives on this day 25 years ago and who we remember here today," Cameron said.