Giotopoulos (l) denies involvement but Koufodinas accepts his own role

The start of the hearing in a bunker-like courtroom built inside a maximum-security prison was marked by arguments and chaotic scenes.

Bulletproof screens set up around the dock were removed after complaints by some of the suspected radicals.

They are accused of murders, bombings and robberies during a 28-year-long campaign of terror.

Reports say the courtroom was packed with spectators, including Athens mayor Dora Bakoyannis whose husband was assassinated in 1989.

We are not trying this case during wartime - [the cage] is an insult to the defendants' personalities and purely theatrical special effects Yannis Rahiotis, defence lawyer

The accused made their presence felt early, with defence lawyers arguing loudly over procedure with the three-judge panel which will decide the case.

But reports say the noisy courtroom fell silent when Dimitris Koufodinas, known as "Poison Hand", the group's alleged top hitman, shouted that he could not hear the proceedings.

He demanded the removal of the bullet-proof screens along three sides of the dock, which was open to the judges.

Correspondents say dozens of lawyers, journalists and relatives of victims and accused had been milling round the cage at the start of what is expected to be Greece's largest case for decades.

Defence lawyer Yannis Rahiotis, who represents alleged leader Alexandros Giotopoulos, also demanded the removal of the cage because it was an abuse of power.

"We are not trying this case during wartime," he said. "It is an insult to the defendants' personalities and purely theatrical special effects."

The judges allowed the request and the screens were removed, to be followed soon by the metal frames.

Many charges

The case is expected to last for months with hundreds of witnesses to be called to give evidence on November 17's alleged killings, bombings and armed robberies.

But Greece's laws mean the suspects cannot be charged with crimes more than 20 years old, such as the 1975 murder of CIA Athens station chief Richard Welch, which was claimed by the gang.

The 18 men and one woman in the dock are expected to face life sentences if convicted.

Mr Giotopoulos has been charged with nearly 1,000 crimes - every one of the attacks blamed on the group within the 20-year statute of limitations.

The authorities want to guarantee a trial beyond reproach Greek Justice Minister Philippos Petsalnikos

He denies involvement in all the crimes, including the killing of British military attache Stephen Saunders in 2000, which prosecutors say was the last of 23 murders carried out by November 17.

Brigadier Saunders, a father of two from Melbury Osmund in Dorset in the UK, was gunned down as he drove to work at the embassy in Athens.

In a newspaper interview Mr Giotopoulos said: "The view that I am the leader of November 17 is an invention of American and British secret services."

In contrast Mr Koufodinas, accused of being the group's chief assassin, has accepted responsibility.

But he says November 17's members are like the "popular fighters" of Greece's War of Independence from the Ottoman empire in 1821.

Media anger

The arrest of suspected members last year, after nearly three decades of failure, was seen as a major boost to Greece, especially ahead of the 2004 Olympic Games in Athens.

Justice Minister Philippos Petsalnikos said: "The authorities want to guarantee a trial beyond reproach... to throw light on an affair that caused pain and damaged the country for 30 years."

The trial is being held amid tight security

But Greek journalists are outraged at a ban on cameras in the courtroom.

Authorities banned live coverage on security grounds and also because they are keen for the hearings not to degenerate into a public spectacle, correspondents say.

November 17 took its name from the date of a bloody student uprising at Athens Polytechnic against the military dictatorship in 1973.

The breakthrough for the police came last June, when a bomb being carried by an alleged member of November 17 exploded prematurely leaving him badly injured and in the hands of the authorities. Within weeks there was a wave of arrests.