(RFE/RL) -- Reports from northwestern China say thousands of troops and police are patrolling the streets of Urumqi, the capital of Xinjiang province, with riot shields, batons, and firearms.
The heavy deployments of security forces follow official media reports said 156 people were killed and more than 1,000 injured in violent ethnic clashes in the city on July 5. Officials say more than 1,400 people also have been detained since then amid continued violence.
Germany's dpa news agency has quoted Dolkun Isa, the secretary-general of the Germany-based World Uyghur Congress, as saying that the Uyghur death toll is now between 600 and 800 -- based on eyewitness reports by phone. Isa said many Uyghurs have been lynched by angry mobs of Han Chinese.
Another congress official, Vice President Asgar Can, warned at a news conference in Munich that the Chinese government should be careful how it responds to the trouble.
"If the government does not come to its senses, if it continues to try to suppress everything with violence, then it is possible that the situation will spread," Can said. "Han Chinese, armed with sticks and big knives, were running in the streets yesterday, chasing after Uyghurs. Anything can happen."
In an address in Urumqi, Chinese Minister of Public Security Meng Jianzhu blamed the violence on Uyghur separatists and told security forces not to let their guard down:
"You all know that this incident was caused by people who want to incite conflict, and its roots are deeply political," Meng said. "This conflict is between separatists and antiseparatist forces, and is an ongoing political struggle."
Meanwhile, Urumqi's Communist Party boss says the government will seek the death penalty for anyone found to be behind the deaths. Li Zhi said many people accused of murder have already been detained and that most were students.
There have also been reports of fresh violence in Urumqi. France's AFP news agency said Han Chinese mobs attacked two Muslim Uyghurs in separate incidents. Reuters reported that riot police tried to disperse a crowd of hundreds of Han Chinese protesters.
Official media say many shops were closed and that some had run out of stocks of food and water. Meanwhile, Internet access remains blocked in Urumqi and in at least two other cities of Xinjiang -- - Kashgar and Turpan.
"If you go to work, you will have to carry a stick or a knife," said Jiang, a 50-year-old resident of Urumqi. "If you don't carry anything like that, that will not work. We will have to carry something for our own safety."
The authorities imposed a nighttime curfew in Urumqi on July 7 to prevent what they described as further "chaos."
The decision was made as hundreds of members of China's predominant Han ethnic group marched through the city carrying metal pipes and other weapons, smashing shops owned by Uyghurs.
Reports said Internet access continues to be blocked in Urumqi and at least two other Xinjiang cities, Kashgar and Turpan.
Authorities said two Uyghurs were killed and 118 people were injured in June clashes that have been blamed for heightening anger ahead of last weekend's violence.
Several Uyghurs -- now under Chinese government protection -- described the scene to Radio Free Asia when Han Chinese laborers stormed the dormitories of Uyghur acquaintances and beat them with clubs, iron bars, and machetes.
"We were taking our meal break after the night shift, when the day shifters [Uyghurs] were sleeping in their dorms," said one, a factory worker who witnessed the violence. "We saw them [Han Chinese] storm into their dorms, pull them out from their beds, and start beating them, hacking and burning. It was around 12:30 a.m. or 1 a.m. Thousands of Chinese, and 800 Uyghurs were there."
The violence at the toy factory was sparked by an online report that Uyghur migrant workers at the factory had raped two Chinese women. Two men have been detained for fabricating that report.
But Chinese officials are blaming the latest riots on foreign influence, including the World Uyghur Congress, although the group's president, Rebiya Kadeer, who lives in exile in the United States, has denied the allegations.
Writing in the "Asian Wall Street Journal," Kadeer repeated her insistence that her group was not involved and condemned the violence by both sides.
"Years of Chinese repression of Uyghurs topped by a confirmation that Chinese officials have no interest in observing the rule of law when Uyghurs are concerned is the cause of the current Uighur discontent," she wrote in the "Wall Street Journal" piece.
In an interview with RFE/RL's Uzbek Service, Kadeer claimed more than 400 people had been killed across China -- not the officially reported figure of 156.
Meanwhile, the Foreign Ministry in Beijing said Chinese President Hu Jintao was cutting short a visit to Italy and returning to China to deal with the situation in Xinjiang. Hu had been scheduled to join the Group of Eight summit that was to open later in the day.
The Russian Foreign Ministry says the violence in Xinjiang is exclusively an internal affair of China, while U.S. Secretary of State Hillary Clinton has called on all sides to exercize restraint.
Turkish Prime Minister Recep Tayyip Erdogan said his government is closely monitoring reports of violence against the ethnic-Turkic Muslim Uyghurs with "concern and regret." Erdogan urged China to bring to justice those responsible for the violence.
The Kazakh Foreign Ministry has advised its citizens not to visit Xinjiang. It said on July 7 that tourist visas were being denied for Kazakh citizens who want to visit the region.
In a statement from the European Union's Swedish presidency, the bloc called for "restraint on all sides" to bring a peaceful end to the unrest and for "the rights of all those in detention [to be] fully respected."
Human rights groups have expressed concerns that detainees could be tortured or mistreated. They also have warned that a harsh crackdown on Uyghurs could exacerbate grievances that have fueled ethnic tensions.
Urumqi is a city of 2.3 million people about 3,000 kilometers of Beijing. Its population is comprised mostly of Han Chinese -- an exception from the rest of Xinjiang, where Muslim Uyghurs make up roughly half the population.
Analysts say the unrest -- the region's worst in years -- underscores ethnic tensions that have accompanied Beijing's growing economic and political stake in China's autonomous western region.
written by RFE/RL correspondent Antoine Blua from Radio Free Asia, RFE/RL, and agency reports