An Albanian murderer who has already used a helicopter to stage two prison breaks has seized hostages in a Greek jail and threatened to blow himself up with them if he is not allowed to escape, police said on Sunday.
Alket Rijai, who is also a convicted robber, barricaded himself into part of the Malandrino jail in central Greece with around five guards late on Saturday, a source in the force told Reuters.
"He is holding a knife and claims to have hand grenades and 200 grams of C4 explosive on him," the police official said.
Officers had surrounded the jail and negotiations had been going on for more than 12 hours, the official said.
At least two other prisoners were with Rijai, but it was not clear if they were hostages or accomplices, the official added.
Rijai has already embarrassed the authorities with two headline-grabbing prison breaks in 2006 and 2009 - using a helicopter in both escapes.
In 2009, a helicopter flew over a high-security prison in Athens, lowered a ladder and whisked him and an accomplice off the roof as guards looked on. The helicopter pilot later said he had been hijacked.
Rijai was arrested a few months after his second escape while sleeping in a hideout in a village northeast of the Greek capital.