A Russian court on Friday found a Danish Jehovah’s Witness guilty of organizing a banned extremist group and sentenced him to six years in prison, Russian state media reported. The case has been condemned by rights groups as part of a broader crackdown on the religious group.

Russia’s Supreme Court banned Jehovah’s Witnesses as an extremist organization in April 2017. About a month later, the police detained Dennis Christensen, a Danish member of the Christian denomination, during a prayer service in the southwestern city of Oryol.

Mr. Christensen, who has lived in Russia since 1999, pleaded not guilty, saying he was exercising his right to religious freedom. He was sentenced to six years in prison, the state-run news agency Tass reported, citing Tatyana Tsukanova, a senior assistant to the prosecutor of the Orlov region.

Paul Gillies, a spokesman for the Jehovah’s Witnesses, said in an emailed statement that Mr. Christensen had been convicted “merely for practicing his Christian faith.”