Updated

Four inmates who had tried to escape from a Greek prison surrendered to authorities after a five-hour standoff on Monday, releasing a total of 28 hostages and handing over a .45-caliber pistol and three kitchen knives, the Ministry of Justice said.

The four include a convicted racketeer and murderer, Panagiotis Vlastos, as well as three members of the armed anarchist group Conspiracy Nuclei of Fire. Authorities would not release the names of the three, although one of them, Michalis Nikolopoulos, gave an interview to a private TV channel.

The hostages were 25 relatives of other inmates who were visiting the prison when the escape attempt occurred, plus three prison guards. The inmates, who released four elderly women a couple of hours before they surrendered, insisted they were not holding the visitors as hostages but that they were trapped by the presence of police outside.

The inmates refused to talk to riot police who had cordoned off streets outside the prison soon after the escape attempt, but negotiated with prison governor Yiannis Anestis. Frangiskos Ragoussis, who represents Vlastos and some of the Conspiracy Nuclei of Fire members, demanded to be let in to see his client but his request was refused by a prosecutor, he told reporters outside the prison.

The escape attempt took place shortly after 6 p.m. local time when Vlastos and the other three, armed with guns, burst through the visitors area and nearly made it into an outside courtyard before prison guards closed the gates on them. The inmates then returned to the visitors are.

In his interview by cell phone to private TV channel Antenna, Nikolopoulos said they had found their weapons "inside the prison."

During the negotiations, the inmates also presented demands for better conditions inside the prison. All other inmates were in their cells, although TV images showed a couple of prisoners burning their mattresses in a show of support.

Having staged two previous escapes from Greek prisons, Vlastos, 41, is currently on trial at a special courtroom set up inside the prison on charges of ordering the kidnapping of shipping tycoon Pericles Panagopoulos. The trial is the reason Vlastos was transferred to Korydallos prison from another jail in central Greece. The trial is at a late stage and the prosecutor has already requested a life sentence for Vlastos.

Panagopoulos, who made his fortune in the cruise and passenger shipping business, was kidnapped in January 2009, allegedly on the orders of Vlastos. Panagopoulos was released eight days later after his family paid a 30 million euro ransom to the kidnappers, most of whom were arrested later.

Vlastos has been involved in racketeering and other criminal activities from a young age, and he first caught the public's attention in the 1990s as a result of a turf war with other crime families, during which he lost one of his two brothers. His other brother was killed in a shootout with police in 1998, during Vlastos' capture from his first escape from prison.

Conspiracy Nuclei of Fire, a group that first became known in 2008 for small arson attacks, went on to bomb the homes of two Greek politicians and a ministry building in 2009. Six of its members were sentenced last July to prison terms ranging from 11 to 25 years for the bombing campaign.

The group became well-known in 2010 after sending mail bombs to foreign embassies in Athens and one parcel that reached the office of German Chancellor Angela Merkel before being destroyed. A trial is pending for these actions.

Korydallos, a maximum-security prison located in a suburb west of Athens, has seen several escapes, the most spectacular of which were the two escapes by helicopter staged by convicted criminals Vassilis Paleokostas and Alket Rizaj in June 2006 and February 2009.