British Prime Minister David Cameron has paid tribute to the "fortitude and resilience" of people affected by the Lockerbie bombing.
He said the 1988 atrocity, which killed 270 people, remained "one of the worst aviation disasters in history and the deadliest act of terrorism" in the United Kingdom.
"The loss of Pan Am Flight 103 over Lockerbie at 7.03pm UK time on the evening of December 21, 1988, was a shocking event," he said, "a loss made more poignant still by being so close to Christmas."
Memories of the 243 passengers, 16 crew and 11 Lockerbie residents who lost their lives had not dimmed.
"Over the last quarter of a century much attention has been focused on the perpetrators of the atrocity. Today our thoughts turn to its victims and to those whose lives have been touched and changed by what happened at Lockerbie that night," he said.