Rights activists have objected to the move, saying it deprives them of their rights and undermines the Kazakh legal system.
Some of the 12 reportedly had ties to the
People's Congress of Kurdistan (Kongra-Gel), an outlawed group labeled
by the Kazakh authorities as a separatist terrorist organization since
RFE/RL's Kazakh Service quoted authorities as saying the men are among an estimated 40 people who left the country illegally between 1995 and 1999 and joined extremist groups in Iran, Iraq, Syria, and Turkey.
About half of those illegal emigres eventually returned to Kazakhstan.
Ninel Fokina, who heads the Almaty office of the International Helsinki Federation for Human Rights, told RFE/RL that individuals suspected of crimes should be tried in courts, not have their citizenship revoked by security officials.
"Even for committing the most horrible, wildest crimes -- brutal murder, treason, or terrorism -- people should be held responsible before the law and according to the law," Fokina says. "But no one has the right to take away someone's citizenship."
Fokina says that the men have a right to appeal to reinstate their citizenships.