The leader of the neo-fascist Golden Dawn party, Nikos Mihallkiakos, one of the four Parliament members, was arrested and charged with forming a criminal organization, The New York Times reported.
The government said last week it had begun a probe into whether members of the violent organization had infiltrated the country's police and military forces.
Golden Dawn has 18 members in Parliament and is the third-most popular party in Greece.
Mihallkiakos said this week all its Parliament members might resign, forcing new elections in the area they represent. A government spokesman said such an action would not force general elections.
Human rights groups say Golden Dawn has terrorized immigrants and police have ignored their violence.
The arrests come less than two weeks after a 45-year-old man who said he was a Golden Dawn supporter allegedly killed a Greek rapper whose music protested the rise of neo-fascism. Two senior police officials later resigned for "personal" reasons and another two were suspended, the BBC reported.
A police officer who was working as a bodyguard at a Golden Dawn party when police raided the party's offices in the town of Agrinio Tuesday was also arrested in the crackdown.
Golden Dawn denies being a neo-Nazi organization, although its members have praised Adolf Hitler and its badge resembles a swastika.
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