Human Rights Watch (HRW) is calling on Russian authorities to drop the charges against a Jehovah’s Witness adherent who is set to go on trial this week, and to put an end to their "ruthless persecution" of the religious group.

On April 3, a criminal court in the central Russian city of Oryol is to begin the trial of Dennis Christensen, a 46-year old Danish citizen who has been in pretrial custody for more than 10 months.

If convicted on charges of "organizing activities of a religious organization that has been declared extremist," the accused faces up to 10 years in prison.

"Russian authorities are seeking to punish a Jehovah’s Witness for exercising his right to practice his religion," Rachel Denber, deputy Europe and Central Asia director at HRW, said in a statement on April 2.

Christensen "did nothing wrong and should be freed," Denber added.

The Jehovah's Witness was detained on May 25 last year during a police raid on a worship service in Oryol.

HRW said he had given a sermon during the service and unlocked the building where the Jehovah’s Witnesses had gathered.

The New York-based human rights watchdog quoted Christensen's lawyer as saying that the charges against his client also stem from his participation in discussions about a religious publication and other actions.

Jehovah's Witnesses have long been viewed with suspicion in Russia for their positions on military service, voting, and government authority in general.

Freedom of religion is formally guaranteed in Russia but legislation sets out Orthodox Christianity, Islam, Judaism, and Buddhism as the country's four traditional religions, and smaller denominations frequently face discrimination.

In April 2017, the Supreme Court labeled the Jehovah's Witnesses an extremist organization, ordering the seizure of its property in Russia and effectively banning worshippers from the country.

Since then, there have been a growing number of reports of worshippers being targeted for harassment.

"The Russian authorities' ruthless persecution of Jehovah's Witness adherents has been picking up steam," Denber said. "Dropping the case against Christensen would be a good first step toward ending the raids and other criminal cases against people who are merely practicing their faith."