Kazakh security services have searched the Almaty office of the unregistered Algha (Forward) party, as well as the homes of the opposition party's leader and several activists.
Algha members told RFE/RL's Kazakh Service that plainclothes officers entered the party's headquarters on the morning of January 23 and barred employees from accessing the building. Police at the scene said they were not authorized to comment on the raid.
News agencies quoted an unnamed party activist as saying the raids were connected to the ongoing investigations of the December 16 deadly unrest in the western Kazakh city of Zhanaozen.
The party's Almaty branch leader, Aizhangul Amirova, has recently been arrested and reportedly been taken to Zhanaozen as a part of the probe.
The "Respublika" online publication reported that some 20 people raided the home of Algha leader Vladimir Kozlov, taking away computers and documents.
Kozlov has been among members of an independent group, which travelled to Zhanaozen on a fact-finding mission last month, shortly after months-long protests by impoverished oil workers turned into violent clashes with police. At least 16 people were killed during the unrest.
State Of Emergency
Kozlov is known as an outspoken critic of strongman Nursultan Nazarbaev, who has ruled the oil-rich Central Asian nation for more than two decades.
Algha emerged from the former Democratic Choice of Kazakhstan, an opposition party banned by authorities in 2005. Kazakh authorities have denied Algha registration, saying most of its registered members were noncitizens.
Zhanaozen remains under a state of emergency which was imposed on the city following the riots. Arrests and interrogations reportedly continue in the remote town.
The riots in Zhanaozen overshadowed Kazakhstan's January 15 parliamentary elections, which were won in a landslide victory by Nazarbaev's Nur Otan party.
The Organization for Security and Cooperation in Europe (OSCE) has concluded the polls failed to meet fundamental democratic standards.
Kazakhstan's Social Democratic party was the only opposition group that was registered to run in the elections. But it failed to make the 7 percent threshold needed to enter parliament.
Algha and other opposition groups -- including Social Democrats and communists -- have formed the Khalyq Maidany (People's Front) opposition coalition, which has strongly criticized the government's handling of the Zhanaozen crisis.