China confirmed on Tuesday that it had cut off Internet access in parts of Urumqi after deadly riots erupted there to prevent the violence from spreading.
"We cut the Internet connection in some areas of Urumqi in order to quell the riot quickly and prevent violence from spreading to other places," said Li Zhi, the top Communist Party official in Urumqi.
Li accused exiled Uighur leader Rebiya Kadeer of orchestrating the violence over the Internet. She denied the charge.
He did not say when Internet access would be fully restored to the city.
Despite Chinese officials' decision to cut off the Internet and mobile phones, pictures, videos and updates from Urumqi poured into social-networking and image-sharing websites such as Twitter, YouTube and Flickr.
Media watchdog Reporters Without Borders accused authorities of wanting to see Urumqi "cut off from the rest of the world."
"Once again, the Chinese government has chosen to cut communications in order to prevent the free flow of information. We firmly condemn this behaviour," Reporters Without Borders said in a statement.
Twitter, YouTube, Wordpress, Blogspot, Wikipedia and a host of other websites were also blocked for users inside all of China on Tuesday.
"Creating an information vacuum in a crisis would be the worst thing to do," Cherian George, a Singapore-based media scholar, told AFP.
"If there are committed provocateurs involved, they will get their disinformation through with or without the Internet."
A technical official working for a state-owned telecommunications company said shutting down the Internet in Urumqi, or parts of the city, was easy.
"You can do it in one second. There is a big backbone network and all you need to do is to switch off the telecom route," the official told AFP, speaking on condition of anonymity due to the sensitivity of the topic.
"The Internet is not just a network. It's actually a point-to-point link between provinces and you can turn off the point that links to the outside," he said.
A shutdown would be even easier in a remote area such as Xinjiang, where the telecommunications network is less developed, said Bjorn Landfeldt, an associate telecoms professor at the University of Sydney.
"As long as you have the mandate to go in and do it, it's a fairly simple operation to target areas or regions because there are not that many links," he said.
Some Urumqi residents said that they were also unable to make calls on mobile phones or send text messages, but others said they experienced no problems.
Pinpointing areas and disabling mobile phone coverage would be easier than shutting down Internet services, Landfeldt said.
"Cell phones are probably even a bit easier because the individual cell towers are very well defined (in terms of) what areas they cover," he said.
"It's really a matter of using a Web interface and clicking on a number of base stations and turning them off," he said, adding stations could also be reconfigured to only stop outgoing calls.
The government has provided Chinese and foreign journalists with Internet access at a media centre in a hotel in Urumqi, the official Xinhua news agency reported.
Xinhua asked Ted Plafker, a journalist for The Economist, to comment on the facilities. He answered: "It would be better if we have Internet everywhere."All rights reserved. © 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.