The death toll from ethnic violence in China's northwest Xinjiang region has risen to 156, and unrest spread to the city of Kashgar, where police dispersed a gathering of 200 people, state media reported.
Angry protesters from the Uighur minority took to the streets of the regional capital Urumqi on Sunday, burning and smashing vehicles and shops, and clashing with anti-riot police.
Over 700 people have been detained for their suspected role in the violence, the official Xinhua news agency reported, although local residents told Reuters police were making indiscriminate sweeps of Uighur areas.
More than 20,000 armed and special police, troops and firefighters were mobilised in a massive crackdown on violence in Urumqi, but despite heightened security some unrest appeared to be spreading in the volatile region.
Around 200 people "trying to gather" at the Id Kah mosque in the centre of the Silk Road city of Kashgar were dispersed by police early this evening, Xinhua said.
Police also had "clues" about efforts to organise unrest in Aksu city and Yili prefecture, the latter a border region that was racked by ethnic unrest in the late 1990s.
Along with Tibet, Xinjiang is one of the most politically sensitive regions in China, and in both places the government has sought to maintain its grip by controlling religious and cultural life while promising economic growth and prosperity.
But minorities have long complained that Han Chinese have reaped most of the benefits from official subsidies, while making locals feel like outsiders in their own homes.
Beijing has said the unrest, the region's worst in years, was the work of separatist groups abroad, who wanted to create an independent homeland for the Muslim Uighur minority.
These groups deny organising the violence and say it was an outpouring of pent-up anger over government policies and Han Chinese economic dominance.
The White House today urged all sides in China's northwestern Xinjiang region "to exercise restraint".
"We are deeply concerned over reports of many deaths and injuries from violence in Urumqi in western China," White House spokesman Robert Gibbs said in a statement.
A peaceful protest of about 1,000 to 3,000 people in the regional capital, Urumqi, apparently spun out of control, as rioters went on a rampage and clashed with police. The official Xinhua News Agency reported hundreds of people were arrested.
The demonstrators had been demanding justice for two Uighurs killed last month during a fight with their Han Chinese co-workers at a factory in southern China. Accounts differed over what happened next in Urumqi, but the violence seemed to have started when a crowd of protesters refused to disperse.
Rioters overturned barricades, attacking vehicles and houses, and clashed violently with police, according to media and witness accounts. State television aired footage showing protesters attacking and kicking people on the ground.
Tensions between Uighurs and the majority Han Chinese are never far from the surface in Xinjiang, China's vast Central Asian buffer province, where militant Uighurs have waged a sporadic, violent separatist campaign. The overwhelming majority of Urumqi's 2.3 million people are Han Chinese.
Agencies