A Libyan man accused of making the bomb which destroyed Pan Am flight 103 over Lockerbie 34 years ago is in United States custody, Scottish authorities have said.
The US announced charges against Abu Agila Masud two years ago, alleging that he played a key role in the bombing on 21 December, 1988.
The blast on board the Boeing 747 left 270 people dead.
It is the deadliest terrorist incident to have taken place on British soil.
All 259 passengers and crew on board the jumbo jet bound to New York from London died while another 11 people were killed in Lockerbie when wreckage destroyed their homes.
Last month it was reported that Masud had been kidnapped by a militia group in Libya, leading to speculation that he was going to be handed over to the American authorities to stand trial.
A US Justice Department spokesperson told the Reuters news agency that Masud would make an initial appearance in a federal court in Washington.
Five years ago he was serving a prison sentence in Libya for bomb-making.
In 2001 Abdelbaset al-Megrahi was convicted of bombing Pan Am 103 after standing trial at a specially-convened Scottish court in the Netherlands.
He was the only man to be convicted over the attack.
Megrahi was jailed for life but was released on compassionate grounds by the Scottish government in 2009 after being diagnosed with cancer.
He died in Libya in 2012.
Megrahi, who always proclaimed his innocence, launched two appeals against his 27-year sentence. One was unsuccessful and the other was abandoned.
A spokesperson for the Crown Office and Procurator Fiscal Service (COPFS) said: "The families of those killed in the Lockerbie bombing have been told that the suspect Abu Agila Mohammad Mas'ud Kheir Al-Marimi ("Mas'ud" or "Masoud") is in US custody.
"Scottish prosecutors and police, working with UK government and US colleagues, will continue to pursue this investigation, with the sole aim of bringing those who acted along with Al Megrahi to justice."
