Security has been tightened in the Xinjiang region of China for the first anniversary of deadly ethnic riots there.
Armed police have been deployed in the main city of Urumqi and thousands of "riot-proof" closed-circuit cameras set up in public places, the BBC reports.
A restaurant owner told the AFP news agency that police had collected all the large knives from his restaurant and advised him to stay indoors on Monday.
A government-run website says all police leave has been cancelled.
The violence that erupted on 5 July 2009 between Uighur Muslims and Han Chinese was the region's worst ethnic violence in decades. Nearly 200 people were killed.
The violence was suppressed by huge numbers of troops deployed in the remote western region.
China officially blamed the violence on the local Uighur population, saying most of the recorded dead were Han. Amnesty International has challenged that version of events, however, saying police used unnecessary force against Uighurs.
Many of the eight million Uighurs in Xinjiang say the influx of Han settlers in recent years has increasingly marginalised their culture.