Masked Russian police raided Jehovah's Witnesses across the country and arrested several in a criminal case accusing the religious group of extremism, it says.

Russia's Supreme Court said Jehovah's Witnesses were an "extremist" organization and ordered it to break up. A 2017 ruling led to the conviction of members across the country.

Jehovah's Witness was established in the U.S. and claims nearly 9 million followers around the world. The group is suspected of illegally resuming its activities in Russia.

Yaroslav Sivulskiy, a representative for Jehovah's Witnesses, told CBS News that at least four of its members had been detained by police. He denied the group had resumed its work.

For years, Jehovah's Witnesses have been under pressure in Russia where the Orthodox Church advocated by President Vladimir Putin is dominant.

In 2018, Putin said he didn't understand why authorities were targeting the group and called for the issue to be evaluated. The Kremlin did not immediately respond to requests for comment.

The government has blocked access to its website.

A court sentenced two Jehovah's Witnesses to four years in jail in September after finding the members guilty of extremism. Jarrod Lopes, the group's U.S.-based spokesman, denounced their sentence as "patently absurd."

According to Sivulskiy, several thousand of Russia's 175,000 Jehovah's Witnesses have left the country since the ban.