Human rights investigators appointed by the United Nations are calling on China to stop its ongoing crackdown on Tibetan Buddhists at monasteries in southwestern China.

The crackdown, reported by scores of witnesses and Tibetan activists through much of 2011, has included the arrests or disappearances of hundreds of monks at the Kirti monastery and other religious facilities in Sichuan province. It is seen by many as a Chinese response to 10 self-immolations by Tibetans protesting widely perceived Chinese intrusions into Tibetan religious practices and customs.

In Geneva Tuesday, the U.N.'s Special Rapporteur on Freedom of Religion and Belief, Heiner Bielfeldt, described the crackdown as repressive and counterproductive. Freedom of opinion expert Frank La Rue protested what he described as allegations of Chinese restrictions on Internet access and mobile messaging services in the region. He urged Beijing to instead “listen to and address the legitimate grievances of the monastic community.”

In a joint statement, the two investigators and others voiced concern over proposed revisions to the Chinese criminal code that would legalize forced disappearances.

Chinese authorities seized more than 300 protesting monks in April from the Kirti monastery, weeks after a protesting monk died after setting himself on fire. Beijing immediately denied involvement in the disappearances, before later admitting the monks were undergoing enforced “legal education” at undisclosed locations.

The U.N. Working group on Enforced and Involuntary Disappearances protested the detentions, accusing Beijing of involvement in enforced disappearances. But China brushed off the U.N. protest, and instead urged critics to adopt a “fair perspective” on government efforts in the region.