SHANGHAI - Independent information about deadly riots in China's remote northwest filtered out on Twitter, YouTube and other Internet forums on Monday, frustrating government efforts to control the news.

The Communist authorities who built the so-called Great Firewall of China raced to stamp out video, images and words posted by Internet users about the unrest on Sunday which, officials said, left at least 140 people dead.

Twitter and YouTube appeared to be blocked in China late on Monday afternoon, while leading Chinese search engines would not give results for "Urumqi", the city in Xinjiang where the riots occurred.

Traditional press also carried only the official version of events, which blamed the unrest on ethnic Muslim Uighurs.

But similar to the phenomenon seen last month during Iran's political turmoil, pictures, videos and updates from Urumqi poured onto social networking and image sharing websites such as Twitter, YouTube and Flickr.

In many cases, items were reposted by other Internet users on sites outside China to preserve the content, while Twitter helped link people around the globe to images Chinese authorities did not want seen.

A US academic in Urumqi appeared to break news about the unrest via Twitter, saying hours before the mainstream news organizations on Sunday night that security forces were blocking off streets in the city.

State-run China Central Television showed its first images of the violence just before midday Monday -- more than 12 hours after footage began circulating on the Internet.

CCTV broadcast images of a woman apparently being kicked as she lay on the ground, protesters throwing stones at police, vehicles on fire, and two young girls with bloodied hands comforting each other.

But its footage gave a different impression to some of the clips on YouTube that Uighur exile groups said backed their case the protesters were largely peaceful.
Footage posted on YouTube showed what appeared to be, at least initially, a peaceful protest, with men and women marching, chatting on mobile phones, sipping bottled water and raising their arms as they cheered.

Another video on the site apparently taken by low-grade video technology in Urumqi showed police in black helmets leading away handcuffed protesters.

Meanwhile some Chinese Internet users were able to express frustration at having their postings on the violence deleted. In one case, Chinese blogger Wen Ni'er reposted an entry on a Google site.

"Chinese mainland websites repeatedly deleted my post, which seriously violated China's law and violated my freedom and rights. I hereby want to express my strong disgust and condemnation," she wrote.

She had help from other anonymous sites based outside of China that were aggregating and saving both official and non-official materials about the incident, such as drop.io/urumuqi.

"I saved them primarily because once the Chinese censors order a take-down, they might not be seen again. Indeed, since I saved them, many of these pictures were 'harmonized' and can no longer be accessed," the site's operator wrote.