A local resident captured part of the escape on video
A massive manhunt is under way in Greece after two criminals escaped from a top security prison by helicopter - for the second time in three years.
Serial armed robber and kidnapper Vassilis Paleokostas, and his Albanian sidekick, Alket Rizai, were days away from trial for their 2006 escape.
They fled Korydallos prison on Sunday after a helicopter landed on the roof and a rope ladder was thrown to them.
Three top prison service officials have been dismissed by the justice minister.
Nikos Dendias said he had sacked the general secretary of the justice ministry, the inspector-general of prisons and the head of Korydallos prison after visiting the facility on Sunday evening.
"This was an insult which I will not accept... I will take measures as harsh as necessary," he told reporters afterwards.
Police also arrested three prison guards and the helicopter pilot on Monday, according to the Associated Press, while Prime Minister Costas Karamanlis has called a meeting to discuss the escape.
The escape happened at about 1530 local time (1330 GMT) on Sunday, the Associated Press news agency reported.
The helicopter was found by a highway in a northern Athens suburb
Guards on the ground opened fire but a woman on board the helicopter shot back with an assault rifle. No injuries were reported.
The helicopter was then found by a highway in the northern Athens suburb of Kapandriti. The pilot had been bound and gagged, and had a hood over his head.
He reportedly told police that the helicopter had been chartered by a couple who wanted to go from the town of Itea in central Greece to Athens, but who later threatened him with an automatic rifle and forced him to fly to the prison.
AP reported that he was later arrested, though this was not confirmed.
Police said the helicopter's fuel tank had been hit by a bullet and was leaking.
The road on which the helicopter was found leads towards Greece's central mountain range, an area where Paleokostas, 42, was able to hide with impunity during previous years, says the BBC's Malcolm Brabant in Athens.
Our correspondent says the breakout is a damning indictment of Greece's prison system.
Three years ago both men managed to escape when a hijacked helicopter landed in Korydallos' central yard at exercise time.
On that occasion, the guards failed to react, because they thought it was a visit by prison inspectors.
Prime Minister Karamanlis has called a meeting to discuss the escape
Paleokostas was previously in prison for a string of crimes including the kidnapping of an industrialist called George Mylonas, released after paying a substantial ransom.
After the previous escape he was recaptured in August 2008.
The architect of that escape, Paleokostas' brother Nikos, has since been captured and jailed, and is now likely to face increased security, our correspondent says.
Even though he was behind bars, Paleokostas is thought to have been involved in the kidnapping of a shipping magnate last year which netted the kidnappers $38m.
An investigation into the previous escape at Korydallos prison recommended it be covered with netting to prevent helicopters from landing.
But the changes were never implemented, our correspondent says.
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