Pussy Riot punk rock group member Nadezhda Tolokonnikova is reported to be in a prison hospital in western Siberia.
She had been on hunger strike protesting against the conditions in prison.
Pyotr Verzilov, her husband, has told the BBC she was undergoing tests for 'various conditions' at a tuberculosis hospital in Krasnoyarsk. But he added that she does not have tuberculosis.
Mr Verzilov said his wife had told him that conditions at the hospital were much better than at a penal colony in Mordovia, where she had been held previously. Her whereabouts had been publicly unknown for 26 days.
Tolokonnikova and two other band members were sentenced to two years in prison last year, after staging an anti-Putin protest in a cathedral in Moscow.
They were charged with hooliganism motivated by religious hatred.
Yekaterina Samutsevich, another member of the group, was released on appeal in October.
The BBC reports Tolokonnikova went on hunger strike after her appeal failed.
