FILE PHOTO: Dennis Christensen, a Jehovah's Witness accused of extremism, leaves after a court session in handcuffs in the town of Oryol, Russia January 14, 2019. REUTERS/Andrew Osborn/File Photo

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”.