Lockerbie bombing: Investigation vow on anniversary
The UK, US and Libyan governments have vowed to work together to reveal "the full facts" of the Lockerbie bombing which claimed 270 lives.
The administrations also expressed their deep condolences to the families of the victims.
The announcement came in a joint statement as memorial events were held on the 25th anniversary of the tragedy.
They said they wanted "all those responsible for this most brutal act of terrorism brought to justice".
The statement by the three administrations said: "On the 25th anniversary of the bombing of Pan American flight 103 over Lockerbie on 21 December 1988, the governments of Libya, the United Kingdom and United States of America reiterate their deepest condolences to the families of the victims of this terrible crime.
"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 this week that Libya had appointed two prosecutors to work on the investigation into the bombing.
The joint statement continued: "We will all provide full support to the investigation team to enable them to complete their inquiries successfully.
"We are striving to further deepen our co-operation and welcome the visit by UK and US investigators to Libya in the near future to discuss all aspects of that co-operation, including sharing of information and documents and access to witnesses."
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.
The joint statement by the three administrations was released as memorial events were being held in the UK and the US to mark the 25th anniversary of the bombing of Pan Am 103 above Lockerbie.
Wreaths were laid at Dryfesdale Cemetery in the town and a service took place in a local church.
Scotland's First Minister Alex Salmond and Lord Wallace, Advocate General for Scotland, were among those who took part in the ceremony.
The service was led by the Rev John MacLeod, while readings and prayers were given by Major Kingsley Layton, commanding officer at Lockerbie Corps, the Salvation Army, and Lord Lieutenant Jean Tulloch, representing the Queen.
During the service Mr MacLeod said: "It is 25 years after the day on which certain men chose to set aside their humanity and destroy the lives of 270 people in the air over this area of Scotland and here in the little town of Lockerbie - not only their lives but also those who survived, families and friends.
"What we the people of Lockerbie in this area will never tire of saying is we welcome you once again to this place where you know you are always welcome.
"In doing so we seek to comfort and console you."
'Bonds of friendship'
Speaking to BBC News after the wreath-laying, Mr Salmond said: "Out of disaster, there are the bonds of friendship.
"Lockerbie has been a welcoming place for the relatives of those who died, and over the last 25 years has taken as good care of people as it possibly could.
"I don't think you ever move on, you certainly never forget, but people do rebuild their lives and many have."
In the US, people gathered at the memorial cairn in Arlington National Cemetery, near Washington DC.
US Attorney General Eric Holder spoke during a ceremony there.
He said: "Although a quarter century has passed since the world was shaken - and so many lives were devastated - by a heinous and cowardly act of terror, no amount of distance or time can ease the pain, or erase the loss, that was inflicted on that day.
"Even now, it remains difficult to comprehend the magnitude of such a senseless crime - which claimed the lives of 259 innocent men, women, and children in the skies above Scotland, along with the lives of 11 residents of the peaceful town of Lockerbie."
There has also been a service at Syracuse University in New York state, which lost 35 students returning from Europe on the Pan Am flight.
Senior Scottish officials and UK government representatives attended a service at Westminster Abbey.
The Reverend John Mosey, whose daughter Helga was killed in the bombing, gave an address during the London service and insisted that the "vicious circle of hatred and aggression" must be broken.
He said: "We remember those we lost with love, sorrow and pain but it is what we do with this other remembering that can affect, not only our personal lives but the wider world we live in."
The Lockerbie bombing remains the deadliest act of terrorism ever committed in the UK and until the attacks of 9/11 it was also responsible for the biggest single loss of American lives in such an attack.
The Boeing 747 was just over half an hour into its flight from London to New York when it exploded, seconds before 19:03 UK time, on 21 December 1988.
'Devastation and horror'
All 243 passengers and 16 crew died, and a further 11 people were killed in their homes when wreckage hit the ground in Lockerbie.
Canon Patrick Keegans, who was parish priest at Lockerbie at the time of the bombing, said the anniversary had "brought to the surface many, many emotions people have had over the past 25 years".
"Other anniversaries have been calmer. This one makes us remember the devastation and horror that all of us experienced 25 years ago," he told BBC Breakfast.
The majority of the passengers and crew on board the aircraft were US citizens.
UK Prime Minister David Cameron paid tribute to the "fortitude and resilience" of those affected by the Lockerbie bombing.
He said: "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.
"To families, friends, neighbours, loved ones, and all those caught up in the painful process of recovery, let us say to them: our admiration for you is unconditional.
"For the fortitude and resilience you have shown. For your determination never to give up. You have shown that terrorist acts cannot crush the human spirit. That is why terrorism will never prevail."
Former Lebanon hostage Terry Waite said he believed the conviction of al-Megrahi was "very shaky indeed" and called for a further investigation into the atrocity.
Speaking after the Westminster Abbey service he said: " I think a thorough, in-depth, further investigation is required to get to the truth, because that's what we owe the families; that truth and justice be done, and I'm not sure we've got to the truth at all yet."