Russia has sentenced six Jehovah’s Witnesses to multi-year prison terms on extremism charges, the religious organization said Thursday.

Rights advocates decry Russia’s prosecutions of Jehovah’s Witnesses — which has been banned in Russia as an “extremist” group since 2017 — as infringements of religious freedom.

A district court in the Siberian city of Krasnoyarsk sentenced engineer Andrei Stupnikov, 47, to six years in prison on charges of “organizing extremist activities,” the Jehovah’s Witnesses said in an emailed statement.

“According to the prosecution, Stupnikov’s fault lies in the fact that he did not renounce his religious beliefs and participated in peaceful services, said prayers, performed chants and Bible discussions,” the group said.

Meanwhile, a court in the city of Kursk has sentenced Andrei Andreev to four and a half years in a prison colony on charges of participating in an “extremist” group. It also sentenced Andrei Ryshkov to three years; Artem Bagratyan to two and a half years; and Bagratyan’s wife Alevtina to two years.

A seventh worshipper, Alexander Vospitanyuk, was handed a two-year suspended sentence.

None of the verdicts have yet entered into force and they can all be appealed.

Andreev, Ryshkov and Artem Bagratyan will remain in jail, while Alevtina Bagratyan will remain under house arrest until the verdict enters into force.

Last year, the U.S. added Russia to its watchlist of religious freedom violators, citing the country’s crackdown on Jehovah’s Witnesses.