China's official Xinhua news agency says police have detained almost 100 ethnic Tibetan monks who attacked a police station in northwestern China.

Carrying a portrait of the Dalai Lama, Tibetan supporters march the streets of Taipei, in protest of the Chinese rule in Tibet (File)

Xinhua says the monks were among hundreds of rioters who assaulted police and government workers at the police building Saturday, injuring some officials. It says the riot happened in the town of Ragya in the Golog Tibetan Autonomous Prefecture of Qinghai province.

The Chinese news agency says police later caught six of the rioters and detained another 89 who turned themselves in. It says all but two of those arrested are monks from a local monastery.

Western news agencies quote a resident of Ragya and a Tibetan exile who lived there as saying the protesters were angry about the apparent suicide of a monk.

Xinhua says the monk escaped from a prison earlier Saturday and jumped into the Yellow River before disappearing.  Chinese authorities had arrested him on suspicion of promoting Tibetan independence.

India-based Tibetan news agencies say the monk, Tashi Sangpo, had raised the banned Tibetan national flag over his monastery on March 10. The date marked the 50th anniversary of the start of a failed Tibetan uprising against Chinese rule.

The reports say Chinese security forces seized the monastery after the incident and claimed to find a Tibetan flag and political leaflets in Tashi's room.

Saturday's protest in Qinghai was one of the most serious outbreaks of unrest in Tibetan-dominated regions of China this year.  Beijing has tightened security in Tibet and neighboring Tibetan regions in recent weeks to prevent commemorations of the 1959 Tibetan uprising.

It is difficult to independently verify accounts of protests and arrests in Tibet and neighboring Tibetan regions because China has barred foreign media from the areas.

Some information for this report was provided by AFP, AP and Reuters.