Greek arrest over CIA chief murder

N17 has claimed responsibility for 23 killings since its first in 1975

ATHENS, Greece (CNN) -- One of the top members of the November 17 terrorist group is denying police charges that he was involved in the group's 1975 assassination of a CIA chief in Athens, Greek police said on Thursday.

Authorities arrested Pavlos Serifis, 46, on Wednesday in the northern village of Argitheas, where he was on holiday, police confirmed.

N17 is a left-wing terror group that is anti-American and opposed to Greek membership of both NATO and the European Union.

It has regularly targeted U.S officials because of the country's support for the military junta that ruled Greece from 1967 to 1974. Until this month no N17 had been arrested.

Counter terrorism officials had been watching Serifis for the past week. Police believe Serifis was partly responsible for the assassination of Richard Welch, the CIA station chief in Athens, 27 years ago.

EXTRA INFORMATION Chronology: N17 terror attacks

The killing was the group's first but since then they have claimed responsibility for a total of 23 killings, including Welch.

Serifis, who worked as a telephone operator for a children's hospital in Athens, was transported to the Greek capital on Wednesday and interrogated by police. He denied any involvement in the N17 group.

Serifis is being detained at police headquarters in Athens and is expected to be formally charged in the coming days.

His arrest brings the total number of suspected N17 members in police custody to 13, including two senior members.

Greek police have carried out a spate of arrests during the past few days

Constantine Telios, 37, turned himself into police on Tuesday and confessed his involvement in at least four attacks blamed on the group, including two assassinations.

Meanwhile, the alleged mastermind of the N17 group, Alexandros Giotopoulos, denied all the charges against him at a court hearing on Tuesday.

Greek police announced the arrest of Giotopoulos, a university professor, last week, saying he is believed to be the organisation's mastermind as well as the author of the proclamations issued by the elusive terrorist group.

The N17 group, which police have long theorised was a small, close-knit group, has gained renown for its ability to elude authorities since Welch's assassination in Athens.

The group is named for the date of a student uprising in 1973 against the military junta that ruled Greece at the time.

While there have been many arrests this month, the organisation has not yet been crushed, Greek Public Order Minister Michalis Chrysoides said earlier this week.

But he said police have dealt the group a severe blow with the arrests and seizures of its stockpiles of weapons.