Greek police arrested Nikolaos Michaloliakos, leader of the nationalist Golden Dawn party, as part of an investigation into alleged criminal activity by the political movement, a police spokeswoman said.

Fellow Golden Dawn lawmakers Ilias Kasidiaris, Yannis Lagos and Ilias Panagiotaros as well as nine other party officials were also arrested today and taken to police headquarters in Athenswhere they are waiting to appear before an investigating judge, said the spokeswoman, who asked not to be identified in line with police-force policy. Arrest warrants have been issued for other party members, including one more Golden Dawn lawmaker, she said.

“Democracy has institutions to protect itself and justice has the means to defend itself and is doing its job,” Simos Kedikoglou, a government spokesman, said in comments televised live on Skai TV.

Greek authorities have stepped up pressure on the movement since one of its supporters killed a 34-year-old man on Sept. 18, leading to police raids on Golden Dawn offices and a judicial probe into whether the party can be banned or characterized as a criminal gang to limit its activities.

Golden Dawn, which denied involvement in the killing, has 18 lawmakers in Greece’s 300-seat parliament. Polls show it has become Greece’s third-most-popular party through anti-immigrant rhetoric.