Updated

Scotland's top legal officer says Scottish police and the FBI visited Libya this week as part of their investigation of the 1988 Lockerbie bombing.

Lord Advocate Frank Mulholland said Friday that a four-person team of Scottish police and prosecutors, along with an FBI delegation, met senior Libyan officials in Tripoli Monday.

The trip was not announced in advance for security reasons.

Mulholland said the discussions "were positive and it is hoped there will be further progress as a result."

The December 1988 bombing of a Pan Am plane over the Scottish town killed 270 people, many of them American.

Libyan intelligence officer Abdelbaset al-Megrahi is the only person convicted over the attack. He was released from a Scottish prison in 2009 on compassionate grounds and died of cancer last year.