The head of the council advising Russian President Dmitry Medvedev on human rights on Friday unexpectedly announced her resignation.
Ella Pamfilova, the activist who headed the president's council on human rights and the development of civil society, said she would not disclose the reasons for her decision for the moment.
Medvedev, a lawyer by training, came to power in 2008 with activists hoping that he would spearhead a transformation of the rights situation in Russia but many have expressed frustration over a lack of progress.
"I have handed in my resignation as chairperson of the council," Pamfilova told the Interfax news agency. "It is my personal decision, no one has forced me, it has not come suddenly."
"I will not discuss the reasons now," she added.
Her announcement comes a day after Medvedev signed into a law a hugely controversial bill expanding the powers of the FSB security service, which activists have slammed as a throwback to the Soviet era.