ATHENS -- The leader of Greece's extreme-right Golden Dawn party and four other of its parliamentarians were formally charged Saturday with membership in a criminal organization with intent to commit crimes, in an escalation of a government crackdown after a fatal stabbing blamed on a supporter.

It was the first time since 1974 that sitting members of Parliament have been arrested. The arrests underline the Greek government's efforts to stifle the fiercely anti-immigrant party, which has been increasingly on the defensive since the killing.

Golden Dawn leader Nikos Michaloliakos, party spokesman Ilias Kassidiaris and Yannis Lagos, Nikos Michos and Ilias Panayiotaros were arrested by counterterrorism police. The last two gave themselves up voluntarily. A sixth parliamentarian, Christos Pappas -- described in a prosecutor's report as the Golden Dawn's No. 2 -- remains at large.

A further 15 people, including 13 Golden Dawn members and two police officers, have also been arrested and are due to appear before a prosecutor and an examining magistrate soon. They face the same charges.

Police spokesman Christos Pagonis told reporters that a total of arrest warrants were issued, all for the same charge; he added that the counterterrorism unit was still searching for the 12 suspects at large, including the missing deputy.

"It is an unprecedentedly dynamic response to a neo-Nazi organization," government spokesman Simos Kedikoglou told The Associated Press, hinting the arrests were the culmination of a long strategy to deal with Golden Dawn as a criminal, not a political force.

"The prime minister and the government were determined to deal with Golden Dawn solely through the justice system ... We have succeeded in stripping them of their political cover and deal with them as what they really are, a criminal organization," Kedikoglou said.

Citizen protection minister Nikos Dendias compared Golden Dawn members to German SS squads.

"The state has proven it is not helpless in the face of organized violence ... Greek society will not tolerate any storm troopers," Dendias said.

The government ordered an investigation into Golden Dawn's activities after the death of rapper Pavlos Fyssas on Sept. 18 sparked outrage across Greece. The suspect arrested over his death admitted to police that he had stabbed the 34-year-old and identified himself as a supporter of Golden Dawn. Police investigated his cellphone records and those of more than 300 people connected to Golden Dawn.

Investigations have extended to the police, which have been accused in the past of turning a blind eye to Golden Dawn violence and of mistreating immigrants.

Under existing anti-terrorism legislation, membership in a criminal organization is a flagrant crime for which the Golden Dawn deputies can be prosecuted without the parliament needing to lift their immunity.

Despite the arrests, the party's lawmakers retain their parliamentary seats unless they are convicted of a crime. Golden Dawn holds 18 of Parliament's 300 seats, after winning nearly 7 per cent of the vote in general elections last year.

The party has vehemently denied any role in the killing, but it has appeared to dent Golden Dawn's appeal among Greeks. As calls for a crackdown mounted, the party hinted its parliamentarians might resign to provoke elections in 15 multi-party constituencies.

"There will be no elections, certainly no general elections," Kedikoglou said. Asked about the likelihood of partial elections if Golden Dawn deputies were to resign, he said "there are ways to deal with that, as well."

"Justice, stability, no elections," Prime Minister Antonis Samaras said as he hurried from his office to the Athens airport on his way to a six-day trip to the U.S.

Samaras was briefed on the arrests by two ministers during a break in his talks with representatives of Greece's creditors.

"Golden Dawn has indeed been losing ground at the polls since the man's murder and I expect them to continue to lose ground. This is the beginning of the end for Golden Dawn," Theodore Couloumbis, a political scientist and professor emeritus of International Relations at Athens University, told The Associated Press.

"There is no provision in the Constitution, and certainly no recent precedent, for the banning of a political party on the grounds of its ideology. That's why the government documented a series of criminal acts to hold them responsible for," Couloumbis added.

A formerly marginal organization with neo-Nazi roots, Golden Dawn entered Parliament for the first time in May 2012, capitalizing on Greece's deep financial crisis, rising crime and anti-immigrant sentiment.

"I think the young man's murder served as a catalyst. Every other political party said 'enough' ... to the violent attacks on Greeks and immigrants alike," Couloumbis said.

Couloumbis also approved the government's intention to avoid even partial elections at this time.

"Even a byelection would be a disaster. It would polarize the country at a time when it begins exiting its worst economic crisis ever," he said.

The party's members and supporters have frequently been suspected of carrying out violent attacks, mainly against immigrants. Despite its reputation for violence, the party had enjoyed growing popularity.

The prosecutor's report says the people under arrest, and those still at large, were responsible for murders, violent attacks, explosions and extortion. The document also said there were indications of laundering of the alleged extortion proceeds.

Police had searched Golden Dawn leader Michaloliakos' home and had retrieved two pistols, an unregistered shotgun, large amounts of ammunition and over US$58,000 in cash, police spokesman Pagonis said. Police also seized computers from Michaloliakos' home.

Pagonis added a search in an arrested police officer's home turned up weapons, including knives, knuckledusters and a stun gun. A Golden Dawn membership card not belonging to the policewoman was also found.

The persons charged are expected to be granted a delay of two or three days to prepare their depositions. Meanwhile, they will be held at Athens police headquarters. It is highly likely that they will remain jailed after those depositions pending trial.