GENEVA (Reuters) – The top United Nations human rights official said on Thursday the harsh prison sentence Russia imposed on a Danish follower of the Jehovah’s Witnesses created a dangerous precedent and violated international law guaranteeing freedom of religion.

A Russian court on Wednesday found Dennis Christensen, an adherent of the Jehovah’s Witnesses, guilty of organizing a banned extremist group and jailed him for six years.

“The harsh sentence imposed on Christensen creates a dangerous precedent and effectively criminalizes the right to freedom of religion or belief for Jehovah’s Witnesses in Russia in contravention of the State’s obligations under the International Covenant on Civil and Political Rights,” Michelle Bachelet, U.N. High Commissioner for Human Rights, said in a statement.

Armed police detained Christensen, a 46-year-old builder, in May 2017 at a prayer meeting in Oryol, about 200 miles (320 km) south of Moscow after a regional court had outlawed the local Jehovah’s Witnesses a year earlier.

Russia’s Supreme Court later ruled the group was “extremist” and ordered it to disband nationwide.

With about 170,000 followers in Russia and 8 million worldwide, Jehovah’s Witnesses are a Christian denomination known for door-to-door preaching, close Bible study, and rejection of military service and blood transfusions.

Christiansen’s detention, Russia’s first extremism-related arrest of a Jehovah’s Witness, foreshadowed dozens more with criminal cases opened against over 100 members of the group, Bachelet said.

At least 18 have been held in pre-trial detention and some have been subjected to house arrest and travel restrictions.

Bachelet urged Russia to revise its laws on combating extremist activity “with a view to clarifying the vague and open-ended definition of extremist activity, and ensuring that the definition requires an element of violence or hatred”.

(Reporting by Stephanie Nebehay, editing by Ed Osmond)