Under arrest: Nikolaos Michaloliakos
Far-right Golden Dawn party leader Nikolaos Mihaloliakos is escorted by anti-terrorism police officers as he leaves the Greek police headquarters in Athens September 28, 2013.

Weapons, ammunition and large amounts of cash have been found at the home of the far-right Golden Dawn leader Nikolaos Michaloliakos following his arrest by Greek police. Michaloliakos has been formally charged with belonging to a criminal organisation.

Four other Golden Dawn members of parliament are in police custody, along with a further 15 party members. During a raid on party offices in Agrinio, western Greece police had to arrest one of their own colleagues, reportedly working as a bodyguard for the party.

At the 2012 election Golden Dawn capitalised on popular anger at anti-austerity measures and attracted 7% of the votes.

Though they admit to being a far-right party, and are opposed to immigration, Golden Dawn deny being fascist. However many of its members wear fascistic uniforms, some have praised Hitler and denied the Holocaust, and the party symbol resembles the Swastika.

The crackdown on Golden Dawn comes after the murder of anti-racist rapper Pavlos Fyssas on 18 September 2013. Golden Dawn sympathiser George Roupakias has been charged with his murder and the Greek Supreme Court deemed the party a criminal organisation.

Government spokesman Simos Kedikoglou hailed what he termed an unprecedented and dynamic response to a neo-Nazi organisation:

"We have succeeded in stripping them of their political cover and dealt with them as what they really are, a criminal organisation."

Unless convicted of a crime the arrested MPs will keep their seats. Golden Dawn has threatened to withdraw all of its 18 MPs in the Hellenic parliament, triggering by-elections that might bring down the coalition.

Last week Michaloliakos, 56, claimed the party were victims of a witch-hunt following the murder of Fyssas:

"We will exhaust any means within our legal constitutional rights to defend our political honour. If the country enters a cycle of instability, it is those who demonise Golden Dawn who will be responsible."

Even some of Golden Dawn's harshest critics are uncomfortable with the crackdown. Constitutional law professor Kostas Chrysogonos says the government have mishandled the situation: "It may have been more correct constitutionally to have sought parliament's approval to lift their political immunity first."