Police in Greece are reported have arrested a man they believe may be the leader of the November 17 guerrilla group.

Government sources described the man as a professor aged about 60.

Saunders was shot four times

An anti-terrorist seized him in a helicopter swoop on the remote Aegean island of Lipsi, just as he was preparing to leave by hydrofoil for a neighbouring island.

He is now being questioned in the capital, Athens.

According to some reports, his wife, a French woman, and former teacher at an Athens college, is also being questioned.

News of the arrest came only hours after police said they had found the gun used in the killing in 2000 of the British attache to Athens, Brigadier Stephen Saunders, which has been blamed on November 17.

The group has been blamed for more than 20 deaths in its 27 years of operations.

French connections

Greek media reports say that the arrested man gave his name as Mikhailis Economou, but was later identified as Alexander Yotopolou.

It is believed he may related to a well-known Greek Marxist with the same family name.

Police are looking for Dimitris Koufodinas

Greek newspapers have portrayed the group's leader as an elderly, left-wing professor with a nom de guerre, Nikitas, who taught at a Paris university between 1967 and 1974, when the Colonels' military junta ruled Greece.

The arrested professor is also said to have studied in France in the 1960s years of student radicalism, and to have visited Cuba.

Police who made the arrest on Lipsi used a fire-brigade helicopter to disguise their arrival.

Earlier on Wednesday, police said ballistic tests had linked a gun used by November 17 to the murders of seven people, including Brigadier Saunders and a Greek politician.

The gun was among an arsenal of weapons found in Athens.

Police are now looking for the alleged tenant of the apartment, named as Dimitris Koufodinas.

Breakthroughs

After failing to make any arrests for 27 years, the Greek police began to make significant progress at the end of last month.

The turning point came as a 40-year-old man, Savvas Xiros, was wounded when a bomb he was carrying exploded prematurely. He is said to be co-operating with prosecutors in return for favourable treatment.

Greece, which is hosting the 2004 Olympics, has been under pressure to crack down on November 17 in the run-up to the games.

The group takes its name from the date of a 1973 student uprising, which was crushed by the army.

November 17 has been blamed for a total of 23 killings.

Its first known attack came in December 1975, when the head of the US Central Intelligence Agency in Athens, Richard Welch, was shot dead.