The leader of Greece's extreme-right Golden Dawn party, Nikos Michaloliakos, is being held in custody after appearing in court Wednesday, the state-run Athens News Agency reported.
Michaloliakos is being held at Athens Police headquarters until it's decided which jail will house him, the agency reported.
He gave a deposition to a Greek court on Wednesday that lasted until the early hours of Thursday morning in Athens, it said. He faces charges of running a criminal organization following the slaying of an anti-fascist musician last month.
There was a heavy police presence outside the court in Athens ahead of Michaloliakos' appearance.
Three other Golden Dawn lawmakers who have already appeared in court -- Elias Kassidiaris, Elias Panagiotaros and Nikos Mihos -- were released Wednesday pending trial. A fourth, Ioannis Lagos, remains in custody.
The arrests of the lawmakers, along with those of a number of party supporters, were part of a weekend police crackdown that followed a controversial stabbing death.
It is the first time since the restoration of democracy in 1974, after a seven-year junta, that a party leader and members of Parliament have been arrested.
Pavlos Fyssas, a popular anti-fascist figure and well-known hip-hop artist with the stage name Killah P, was the victim of a knife attack that was allegedly committed by a Golden Dawn supporter.
Kassidiaris denied his party's involvement in Fyssas' death, calling it a "heinous crime."
The singer's death has nevertheless led to renewed calls to ban Golden Dawn, which holds 18 of Parliament's 300 seats.
The Greek constitution does not allow for political parties to be banned, however, and the arrested lawmakers will retain their parliamentary seats unless they are convicted of a crime.
In 2012, Golden Dawn rode a wave of dissatisfaction among some Greeks -- spurred by internationally imposed austerity measures amid the country's deep financial crisis -- to win 7% of the vote and gain seats in Parliament for the first time.
The ultranationalist, anti-immigration party has been linked by critics to street violence and neo-Nazism.