Greece is continuing its crackdown on the far-right Golden Dawn party.
On Thursday, the deputy leader of the Neo-Nazi party, Christos Pappas, was remanded in custody on charges of organizing a criminal group, reported the BBC.
The party's leader Nikos Michaloliakos, and one of its MPs, Yiannis Lagos, have been moved to a high-security prison, pending their trial on similar charges.
Six MPs from the far-right party were arrested at the weekend.
Golden Dawn leaders deny charges linking them to the killing of a left-wing activist by a party supporter.
There was outrage in Greece after Pavlos Fyssas, a hip-hop musician, was stabbed to death last month. Amid street protests, Prime Minister Antonis Samaras' conservative-led government has promised to "eradicate" Golden Dawn.
"This is the most dynamic confrontation of a neo-Nazi criminal organization in European history, perhaps in world history," the AFP news agency quoted a government spokesman, Simos Kedikoglou, as saying.
Nikolaos Mihaloliakos, 56, is the first elected party chief in Greece to be held in prison in more than 30 years.
As police marched him out of the courthouse, he shouted, "Long live victory!''. It was a direct translation of the Nazi "Sieg Heil'' slogan.
Dozens of people have been arrested in the ongling crackdown against Golden Dawn. Several police officers face charges ranging from illegal weapons and ammunition possession, to abuse of power.
Michaloliakos' party gained support from voters discontented with economic crisis and on-going austerity measures. However there were widespread accusations that it organized attacks on immigrants, political opponents and homosexuals.
Golden Dawn has denied the claims. The party's popularity has waned since the killing of Fyssas.
The party has become notorious for its blatant anti-Semitic and xenophobic rhetoric, openly displaying copies of “Mein Kampf,” as well as other works on Greek racial superiority at party headquarters.
Michaloliakos has claimed that Nazi concentration camps did not use ovens and gas chambers to exterminate Jews during the Holocaust.
Samaras recently pledged to eradicate the "shame" of neo-Nazism in the country.
"We are dedicated in completely eradicating such a 'shame'," Samaras said in a speech to the American Jewish Committee in New York.
"We must do it within the context of our democratic constitution. But we have to go all the way and do whatever it takes," the premier said, according to a text released by his office.