China's top security official has warned of a new crackdown on "separatism" in the remote north-western region of Xinjiang.
Some Uighurs resent an influx of Chinese settlers to the region
The warning came ahead of ceremonies planned for 1 October to mark half-a-century of Chinese control.
Luo Gan said officers should remain "prepared for danger".
Xinjiang is home to a large population of Muslim Uighurs, some of whom want an independent homeland in the region they call East Turkestan.
Many resent the recent and large-scale influx into the region of Han Chinese settlers, though there have been few reports of violence.
Ethnically Turkic Muslims, mainly in Xinjiang
Made bid for independent state in 1940s
Sporadic violence in Xinjiang since 1991
Uighurs worried about Chinese immigration and erosion of traditional culture
China brands the separatists as terrorists and said earlier this month that more than 260 terrorist acts had been committed in Xinjiang in the past two decades.
Mr Luo said the general situation in Xinjiang was very good, according to the China Daily, but he called on officials at all levels to "be prepared for danger in times of safety".
The authorities last month accused a prominent Uighur businesswoman-turned-activist, Rebiya Kadeer, who was recently freed from jail under intense international pressure, of planning to sabotage the forthcoming ceremonies.
Ms Kadeer has since gone into exile in the United States.