Violence in China's restive western region of Xinjiang has left at least 140 people dead and more than 800 people injured, state media say.The Chinese government must be on a hair-trigger right now, considering the Iranian case, their rising unemployment, and the growing sense that economic growth is not going to continue indefinitely. I'd be suprised if we don't see more of this. Unfortunately.
Several hundred people were arrested after a protest, in the city of Urumqi on Sunday, turned violent.
Beijing says Uighurs went on the rampage but one exiled Uighur leader says police fired on students.
The protest was reportedly prompted by a deadly fight between Uighurs and Han Chinese in southern China last month.
The BBC's Chris Hogg in Shanghai says this is one of the most serious clashes between the authorities and demonstrators in China since Tiananmen Square in 1989.
Eyewitnesses said the violence started on Sunday in Urumqi after a protest of a few hundred people grew to more than 1,000.
Xinhua says the protesters carried knives, bricks and batons, smashed cars and stores, and fought with security forces.
Wu Nong, news director for the Xinjiang government, said more than 260 vehicles were attacked and more than 200 shops and houses damaged.
Most of the violence is reported to have taken place in the city centre, around Renmin (People's) Square, Jiefang and Xinhua South Roads and the Bazaar.
The police presence was reported to be heavy on Monday.
Adam Grode, an American studying in Urumqi, told Associated Press: "There are soldiers everywhere, police are at all the corners. Traffic has completely stopped."
A witness in the Xinjiang city of Kashgar told AP there was a protest there on Monday of about 300 people but there were no clashes with police.
It is still unclear who died in Urumqi and why so many were killed.
The Xinjiang government blamed separatist Uighurs based abroad for orchestrating attacks on ethnic Han Chinese.
But Uighur groups insisted their protest was peaceful and had fallen victim to state violence, with police firing indiscriminately on protesters in Urumqi.
Dolkun Isa, a spokesman for the World Uyghur Congress (WUC) in Munich, disputed the official figures, saying the protest was 10,000 strong and that 600 people were killed.
He rejected reports on Xinhua that it had instigated the protests.
Xinhua had quoted the Xinjiang government as blaming WUC leader Rebiya Kadeer for "masterminding" the violence.
But Mr Isa said the WUC had called on Friday only for protests at Chinese embassies around the world.
Alim Seytoff, the vice-president of another Uighur group - the US-based Uighur American Association - condemned the "heavy-handed" actions of the security forces.
"We ask the international community to condemn China's killing of innocent Uighurs. This is a very dark day in the history of the Uighur people," he said.
When asked about the rioting, UN Secretary General Ban Ki-moon said that all governments must protect freedom of speech and "the life and safety of civilian populations".
A spokesman for UK PM Gordon Brown said Britain was urging "restraint on all sides".
Edit: Subsequent stories put it across that the violence has ben primarily Uighur-on-Han, not Han-o-Uighur. I'm skeptical about that: this piece in the Brisbane Times compelling demonstrates victims on both sides. The problem, naturally, is that we don't know what's really going on. The censorship wall in China is too strong.
Anyway, I'm doing a follow-up.