Almost 100 Tibetan monks were being held after an apparent riot in a remote north-western town, Chinese state media said on Sunday, in the clearest indication so far that Tibetan areas are seeing widespread renewed unrest.

The account by Xinhua, the official news agency, of an “attack” on a police station in a Tibetan-populated area in Qinghai province could not be checked for its accuracy because the Chinese government has kept all Tibetan areas locked down and imposed a de facto news blackout amid a series of sensitive anniversaries this month.