The police in Greece think they may have finally arrested Muhammed Ali Hamadi, a notorious Hezbollah terrorist who took part in the 1985 hijacking of a TWA jet in which a US Navy sailor was tortured and killed.

But some sources in the US have said they don't believe the Greeks have got the right man.

The suspect was arrested on a cruise ship near the party island of Mykonos.

A Greek source told Insider that biometric data prompted the arrest.

Greek police today continued working to identify a 65-year-old Lebanese man arrested disembarking from a cruise ship on the island of Mykonos last Thursday on suspicions he was involved in the 1985 hijacking of TWA flight 847.

The man was identified by Lebanon's foreign ministry as journalist "Mohammed Salah" but Greek police and intelligence officials reportedly believe the suspect might actually be Muhammed Ali Hamadi, a notorious Hezbollah operative who had been previously convicted and sentenced to life in prison in Germany for the hijacking and an unrelated bomb plot.

However, the brother of a US Navy sailor tortured and killed in the 1985 hijacking told the American press that he was told by the US Department of Justice that the man in custody is not Hamadi. Americans officials have long wanted Hamadi extradited to the US to face trial for the TWA hijacking and the murder of the sailor.

Greek officials have not commented and the suspect remains in jail.

Greek officials did not return calls for comment on the discrepancy but one police official speaking on background to Insider said that biometric data led to the arrest. Hamadi was said to be in his late 30s in 2005, which would put him in the same age range as the detained suspect.

396463 03: The Mukefaha, a Lebanese Army anti-terrorism special unit, train at the Beirut International Airport October 26, 2001 in Lebanon. The same airport was the scene of the 1985 TWA Flight 847 hijacking during which U.S. Navy diver Robert Stethem was shot dead. (Photo by Courtney Kealy/Getty Images)

Much to the fury of US officials, Germany was forced to release Hamadi on parole to Lebanon in 2005 after a German national was kidnapped by Hezbollah (or its allies) in Iraq. The hostage, a prominent German archaeologist, was released unharmed after Hamadi was paroled and deported to Lebanon, which has since refused to act on US demands for his extradition.

The suspect is currently being held in a prison on Syros, near Mykonos, and will be transferred to Athens this week to face extradition hearings on both German and American warrants. The US is expected to push hard for their warrant to take priority over Germany's in part because of concerns that he would be released again.

If the Greek police are correct and the suspect is confirmed to be Hamadi, it will reopen an unexpected chapter in the career of one of Hezbollah's highest-profile operatives.

Hamadi is accused of helping mastermind the 1985 hijacking with Imad Mughniyeh, the Hezbollah master terrorist who was accused of a slew of attacks and kidnappings against US, French, Israeli and other targets from 1981 to 2008, when he was killed in a joint Mossad-CIA operation in Damascus.

Hamadi was originally arrested in Germany, while carrying bomb-making components in 1987 and convicted of hijacking and murder before being held for 19 years prior to his 2005 release.

The hijacking of TWA Flight 847 stunned the US in 1985. Two armed men stormed the cockpit of the plane as it departed Athens for Rome before being scheduled to continue to San Diego. They diverted the plane to Beirut, where US Navy sailor Robert Dean Stetham was beaten, shot, and dumped on the tarmac as the plane was refueled, and more heavily armed hijackers, including Mughniyeh, joined the operation.

A Shi'ite Muslim gunman talks to one of the hijackers of a TWA plane at Beirut airport in this file photo taken in June 1985. One of the hijackers, Mohammad Ali Hammadi, was released by Germany last week after serving nearly 19 years of a life sentence for his role in the 17-day hijack drama and the killing of U.S. Navy diver Robert Dean Stethem. REUTERS/Jamal Saidi/Files

The ensuing days saw the plane repeatedly fly between Algiers and Beirut, as Hamadi and Mughniyeh demanded the release of 17 Hezbollah operatives held in a plot to truck-bomb the US Embassy in Kuwait, as well as hundreds of Lebanese prisoners held by Israel, which occupied most of southern Lebanon at the time.

Eventually, the hostages were taken to sites in southern Beirut and their freedom was negotiated by Lebanese officials with the last released two weeks into the incident.

US officials have long sought Hamadi for Stetham's murder as well as the hijacking and were livid when Germany decided to parole his life sentence, while ignoring the US extradition demand and allow him to disappear into Lebanon.

Hamadi remains on the FBI's list of most-wanted terrorists with a $5 million bounty on his head for information leading to his arrest. He joins a slew of other Hezbollah operatives that Lebanon refuses to arrest, including two other hijackers from the 1985 operation; four men accused of plotting the 2005 car bomb murder of former Lebanese prime minister Rafiq Hariri after being tried in absentia by a UN special tribunal; as well as two suspects in a 2012 suicide bombing against Israeli tourists at a Bulgarian Black Sea resort.

Lebanon has officially claimed that it lacks information on the suspect's locations, but privately officials concede that the Lebanese government lacks the ability to confront Hezbollah and arrest its members.