The Chinese government says the death toll from a police clash with ethnic Uighurs late Sunday in the Xinjiang autonomous region has risen to 156, and is still climbing.
Uighur exile groups deny being involved, saying unrest resulted from Uighurs' building frustrations with what they feel are excessive controls by the Han Chinese on economic opportunities, culture and religion.
State television Monday was filled with images of violence and bloodshed on the streets of Urumqi, the capital of Xinjiang.
Official media say nearly 1,000 people were hurt or killed, and more than 200 shops and buildings, and 260 vehicles were burned.
The head of Xinjiang's Public Security Bureau, Liu Yaohua, said minority Uighur protesters used an incident last month in Guangdong province as an excuse to riot.
Liu says the incident - which involved a clash last month between Uighur factory workers and Han Chinese in southern China - was treated as a straightforward criminal case. Two Uighurs died in that violence.
During Sunday's riots nearly 3,000 Uighurs protested last month's clash.
China has accused the Uighurs of seeking independence for Xinjiang, and says foreign groups fan the flames of separatism. Official Chinese statements especially blame the World Uighur Congress, led by Rebiya Kadeer, a Uighur businesswoman who spent years in jail in China and now lives in the United States.
A foreign journalist in Urumqi described a heavy security presence - with armored personnel carriers and water cannons out in force. The journalist says the security presence is heavy in the southern part of town, which is where the Uighur minority live. The journalist also says as of Monday, security forces are still arresting people.
People in the Urumqi also report Internet service was out Monday.
The World Uighur Congress in Germany issued a statement condemning what it describes as Chinese security forces' "brutal crackdown of a peaceful protest" by young Uighurs. The statement quotes Uighur witnesses as saying scores of protesters were killed and dozens were injured after authorities used lethal force to disperse the protesters.
The group also rejected China's accusation that it "masterminded" Sunday's events.
Xinjiang is at China's western border. Almost half of Xinjiang's 20 million people are Uighurs, who primarily are Muslims. Many in the minority group resent controls imposed by Beijing and the large influx of Han Chinese migrants into the region. The population of Urumqi is mostly Han Chinese, and under normal times the city is under tight police security.