BEIJING - The brawl between Han Chinese and Uighurs in southern China was scarcely covered by state media, but accounts and photos spread quickly via the Internet and became a spark that helped ignite deadly riots thousands of miles away in the Uighur homeland.

Even in tightly controlled China, relatively unfettered commentaries and images circulating on Web sites helped stir up tensions and rally people to join an initially peaceful protest in the Xinjiang region that spiraled into violence Sunday, leaving more than 150 people dead.

In China, as in Iran and other hotspots, the Internet, social networking and micro-blogging are playing a central role in mobilizing people power — and becoming contested ground as governments fight back.

In the Internet age, events in "places like Xinjiang or Tibet, which were always considered very remote," can suddenly become close and immediate for people around the world, said Xiao Qiang, director of the Berkeley China Internet Project at the University of California-Berkeley.

Since the outburst in the Xinjiang capital of Urumqi, the Chinese government has blocked Twitter and Facebook, scrubbed news sites, unplugged the Internet entirely in some places and slowed it and cell phone service to a crawl in others to stifle reports about the violence — and get its own message out that authorities are in control.

Key-word filters have been activated on search engines like Baidu and Google's Chinese version so that searches for "Xinjiang" or "Uighur" only turn up results that jibe with the official version of events.

That a fight in one part of China could impact a riot 10 days later thousands of miles away underscores how slippery fast-evolving communication technologies can be even for an authoritarian government with the world's most extensive Internet monitoring system.

State media reports said only two people died in the June 25 fight between Uighur and Han Chinese workers at a toy factory in southern Shaoguan city. In the days that followed, however, graphic photos spread on the Internet purportedly showing at least a half-dozen bodies of Uighurs, with Han Chinese — members of China's majority ethnic group — standing over them, arms raised in victory.

Expunged from some sites, the photos were posted and reposted, some on overseas servers beyond the reach of censors. Their impact was amplified by postings on bulletin boards and other sites.

Uighurbiz.cn, a site popular among Uighurs, carried an open letter over the weekend suggesting there would be revenge for the factory fight. "You've beaten Uighurs, killed Uighurs and perhaps never thought about the consequences," said the letter posted by someone using the Uighur alias Yadkar.

A flurry of postings on another popular site, Diyarim.com, began calling for action in Urumqi. Diyarim's founder, Dilixati, remembers one: "Gather at 5 p.m. at People's Square. Young people if you have time come to the square." The messages kept reappearing, and he called police to alert them and took the site off-line, said Dilixati, who would give only his first name for fear of reprisals.

Hours after Sunday's riot, when police were still trying to pacify Urumqi's streets, Xinjiang's leaders went on TV to denounce Uighur separatists living abroad for using Diyarim and Uighurbiz to organize the disturbance.

That the riot occurred in Urumqi may be testament to its being the most-wired place in Xinjiang, a remote region of vast deserts and towering mountains that juts into Central Asia.

Mobile phone coverage is typically stable in the city and people use handheld devices to go online, said Dru Gladney, a Uighur expert at the Pacific Basin Institute at Pomona College in California. In Urumqi, "people have these technologies literally at their fingertips," he said.

Elsewhere in Xinjiang, the best services are provided at closely monitored Internet cafes, where Uighurs may be less comfortable posting sensitive information, Gladney said.

Only a dozen years ago, when China was scarcely wired, details of the authorities' brutal quelling of a similar protest by Uighurs in the city of Yining leaked out slowly and even today remain obscure. An official death toll of nine is disputed by exiled Uighurs and rights groups who say fatalities may have been 10 times that or greater.

Unplugging Internet and cell phone service has become standard practice for dealing with civil unrest. The government did so in March over worries about renewed anti-Chinese demonstrations in Tibetan areas.

Though officials usually prefer to keep silent about such tactics, Urumqi's top Communist Party official, Li Zhi, told a news conference Tuesday that the Internet was deliberately cut off in parts of the city. He said it was done "in order to quench the riot quickly and prevent violence from spreading to other places."

Such censorship does not quiet unrest for long, but instead ends up giving rumors more credence than they deserve, said Berkeley's Xiao.

"The more you try to police the Internet, and delete information, the more those rumors become some kind of truth and people just pick what they want to believe," said Xiao. "That's the negative direct consequences of such tight information control."

(Source: http://tech.yahoo.com/news/ap/20090707/ap_on_hi_te/as_china_wired_uighurs)