Alket Rizaj, an Albanian who has escaped from prison twice already, has been locked in tense negotiations with police for nearly 18 hours. Authorities say he is demanding a getaway car.
Officials in Greece's Justice Ministry also said Sunday that Rizaj is holding five hostages at the central Malandrino prison, with another having either escaped or been released. They spoke on condition of anonymity because they were not authorized to speak to the press.
They also said Rizaj claims to have explosives, guns and a grenade.
Rizaj, convicted for multiple murders, has escaped twice before, in 2006 and 2009, from Korydallos maximum security prison in Athens, both times by helicopters that picked him and another convict, Vassilis Paleokostas, from the prison's courtyard.