BERLIN (AP) — Prosecutors in Berlin and the neighboring German state of Brandenburg are interviewing former members of East Germany's secret police about the 1988 Lockerbie plane bombing, according to officials and media reports.

All 259 people on board and 11 people on the ground were killed when Pan Am Flight 103 ?blew up over the Scottish town of Lockerbie on its way to New York and Detroit on Dec. 21, 1988.

Berlin prosecutors said Thursday on Twitter they have received a request for assistance from Scottish authorities "on the basis of which several alleged Stasi employees are questioned, including in Berlin."

German news agency dpa reported that prosecutors in Frankfurt an der Oder, 80 kilometers (50 miles) east of Berlin, received similar requests. The ex-Stasi agents are considered possible witnesses, not suspects.

According to German daily Bild, which first reported the story, almost 20 former Stasi employees are being sought for questioning in the Lockerbie bombing.

Libyan Abdelbaset al-Megrahi was convicted of the bombing in 2001. He maintained his innocence until death in 2012, and Al-Megrahi's family is seeking to overturn his murder conviction, citing concerns about the evidence.

Bild reported that Scottish prosecutors are investigating whether the Stasi agents may have been part of a plot to bomb the plane, which was ordered by then-Libyan dictator Moammar Gadhafi. Most of those questioned were members of the Stasi's Department 22, which had contacts with extremist groups in Western Europe, the paper reported.