(CNN) -- Bahrain has revoked the citizenship of 31 Shiite activists, the latest clampdown on the opposition amid continued unrest in the Persian Gulf kingdom.
The state-run Bahrain TV announced the move Tuesday evening, citing an Interior Ministry statement. The television anchor read out the names of the 31 activists, which included Jawad Fairouz, a former member of parliament for the Shiite opposition group Al-Wefaq, and his brother, Jalal.
Among the other prominent opposition figures who were stripped of their citizenship were Said al-Shihabi, the head of the Freemen of Bahrain movement, and Ali Hassan Mushaima, the son of the leader of Al-Haq group.
Also on the list were three Shiite clerics: Hussein Mirza, Khaled Mansour Sanad and Alawi Sharaf.
The Interior Ministry statement Tuesday said the country's Citizenship Act "allows the kingdom the right to revoke the citizenship of anyone who is charged with being a threat to the state's security," Bahrain TV reported. Those who object to the decision have the right to challenge it in court, it added.
Two prominent Bahraini groups, the Bahrain Youth Society for Human Rights and Bahrain Center for Human Rights, decried the move.
The groups said they had "grave concern over the systematic targeting of prominent political activists, former members of parliament, clerics and others. The Bahraini authorities did not provide substantial evidence as to why these individuals' citizenships have been revoked."
Rights group Amnesty International similarly condemned the move.
"The authorities have provided the vaguest of reasons for the deprivation of nationality, which appears to have been taken on the basis of the victims' political views," said Philip Luther, Amnesty International's director for the Middle East and North Africa.
"Most worryingly, the authorities are making some in the group stateless. This, as well as any arbitrary deprivation of nationality, is prohibited under international law," he said.
"We urgently call on the Bahraini authorities to rescind this frightening and chilling decision."
Bahraini authorities imposed a ban late last month on public protests, saying it was necessary to rein in violence. But Amnesty International said the move breached people's right to free speech.
Violent clashes have broken out between security forces and opposition protesters on numerous occasions since protests began in the island nation in February 2011, spurred by uprisings in Tunisia and Egypt.
Bahrain's ruling Khalifa family is Sunni Muslim, but about two-thirds of the country's people are Shiite.
The country is strategically important for the United States in the region and it is home to the U.S. Navy's 5th Fleet.
CNN's Mohammed Jamjoom contributed to this report.