Just ahead of the first anniversary of deadly riots by Tibetans protesting against Chinese rule, security has been stepped up in the areas affected.Riot police are patrolling the streets of Tongren in Qinghai province. The boost in security also comes ahead of the 50th anniversary next month of the exile of the Dalai Lama. The military is on high alert in Tibet itself and in neighbouring areas with many ethnic Tibetans. One monk in Qinghai said: “Last year they were holding the Olympics and they were worried about giving a bad impression. They were a bit more relaxed. But this year they control us very strictly.” Other monks have complained about intimidation by armed forces, while one report says a monk set himself on fire in a protest on Saturday. China says 21 people died in the riots that broke out in March last year; Tibetans put the death toll at more than 200.