The US will soon announce charges against a Libyan suspected of making the bomb that blew up Pan Am Flight 103 over Lockerbie in 1988, US media say.
Prosecutors will soon seek the extradition of Abu Agila Mohammad Masud to stand trial in the US, reports say.
He is currently being held in Libya, according to the Wall Street Journal. This has not been confirmed by the Libyan authorities.
The blast on board a Boeing 747 over the Scottish town left 270 people dead.
Most of the victims on board the flight from London to New York were American citizens. Eleven people on the ground were also killed.
It remains the deadliest terrorist incident ever to have taken place on British soil.
Libyan national Abdelbaset al-Megrahi was the only man convicted, in 2001, over the bombing.
Megrahi, who always proclaimed his innocence, launched two appeals against his 27-year sentence, one was unsuccessful and the other was abandoned.
Megrahi was released from prison in Scotland and allowed to return to Libya on compassionate grounds in 2009 after it emerged that he had terminal cancer. He died three years later.
A Scottish court is now considering a posthumous appeal against his conviction by his family.