Greek police have arrested the leader, two lawmakers, and other members of the far-right Golden Dawn party. They have charged one member with being an accomplice to the killing of an antifascist rapper.
Party leader Nikolaos Mihaloliakos, spokesman Ilias Kasidiaris, two other lawmakers, and 10 members had been arrested on charges of founding a criminal organization.
They are due to appear in court this weekend to be formally charged.
The arrests come several days after left-wing activist rapper Pavlos Fissas died when he was stabbed on September 17 by an alleged Golden Dawn sympathizer.
A man with suspected ties to Golden Dawn has already been charged over the killing. The party has denied any role in the murder, which sparked violent protests in Athens.
The arrests on September 28 marked the biggest crackdown against a political party in Greece since the fall of Greece's military junta in 1974.
However, the government played down the impact of the detentions. Finance Minister Yannis Stournaras told reporters in Athens that there "is no risk of destabilization."
Stournaras was speaking after a meeting in which Prime Minister Antonis Samaras briefed Greece's European Union and International Monetary Fund lenders on the crackdown against Golden Dawn.
On the streets of Athens on September 28, local resident Nick Tzimas told reporters that those responsible for the murder of Fissas should face justice.
"Whoever is responsible for any murder should be going to jail regardless of which party they belong to," he said.
Another resident, Nikos Valakis, suggested that not only Golden Dawn members, but other politicians suspected of corruption should be prosecuted.
"Of course, they should go to jail if they find evidence," he said. "But there should be justice for everyone, not just Golden Dawn. They should also arrest those who have stolen from and lied to the people."
Golden Dawn, which has neo-Nazi roots, was founded in 1993 but entered parliament for the first time only in May 2012, garnering 7 percent of the vote and gaining 18 seats.
The party has seen its popularity increase amid a harsh financial crisis and growing anti-immigrant sentiment.
Golden Dawn had scored 14 percent of voter support in opinion polls before the stabbing.
But a poll this week showed its backing had fallen to under 7 percent.
With reporting by Reuters, AP, and dpa