Human rights experts appointed by the U.N. on Nov. 1 called on China to stop repressive measures against Tibetan Buddhist monks, including arrests and enforced disappearance.

Security forces using riot gear, automatic rifles and trucks have been deployed at the Kirti monastery, which houses some 2,500 monks, and other monasteries in Aba County, an area of Sichuan province, the experts said. The monks have protested Chinese rule of Tibet. The U.N. experts said Chinese authorities have carried out security raids and surveillance within monasteries to monitor religious activities.

“Intimidation of the lay monastic community must be avoided, and the right of members of the monastic community and the wider community to practice their religion, should be fully respected and guaranteed by the Chinese government,” said Heiner Bielefeldt, U.N. special representative on freedom of religion.

Rita Izsak, the U.N. independent expert on minority issues called on the Chinese authorities to “fully respect and uphold the rights of minorities, including their rights to freely practice their religion and culture.”

Jeremy Sarkin, chairman of the U.N. working group on enforced or involuntary disappearances said, “Any enforced disappearance is unacceptable and such practices are in violation of international law.”

The U.N. General Assembly declared in 1992 that an enforced disappearance occurs when “persons are arrested, detained or abducted against their will or otherwise deprived of their liberty by officials of different branches or levels of government ... followed by a refusal to disclose the fate or whereabouts of the persons concerned.”

Sarkin expressed concern that a proposed amendment to Chinese criminal law will legalize enforced disappearance, saying, “this heinous practice is not permitted under any circumstances.”

Nine monks and one nun have reportedly self-immolated since March in the province in support of religious freedom, according to Free-Tibet advocacy groups.

Ravina Shamdasani, a spokeswoman for the U.N. High Commissioner for Human Rights, told a news briefing her office regrets “the tragic loss of the lives of these monks ... and we do call on the concerned authorities to do what they can to diffuse the tensions, and to prevent further such cases.”