Nearly four months after deadly ethnic riots in China's Muslim region led authorities to shut off the Internet there, local residents are still barred from sending text messages and getting online.

The clampdown on telecommunication in China's western Xinjiang province, where rioting claimed nearly 200 lives in early July, has hurt local businesses and cut residents off from many nongovernment sources of news and other information.

The rioting between Uighurs, a mostly Muslim minority group native to Xinjiang, and Chinese Han, the country's ethnic majority, also led China to block various social networking Web sites nationwide. Twitter, similar Chinese services and Facebook all remain inaccessible in the country. China has blamed communication on such Web sites for helping lead to the riots, which were sparked by an ethnic brawl in far-away southern China.

Observers have cited a series of sensitive anniversaries this year as a reason for the blockages, but those dates, including China's 60th anniversary of communist rule on Oct. 1, have passed.

"The unfortunate truth is that the Chinese government can impose and sustain this kind of Internet service disruption ... for as long as it feels it's necessary," said Phelim Kine, a researcher in Hong Kong for New York-based Human Rights Watch. "The government is impervious to concerns from the business sector and certainly those of ordinary citizens."

Some companies have been allowed to communicate via a regional network in Xinjiang, said the marketing manager for one local company when reached by phone. The manager predicted that regular Internet access could return in around one month.

"It's relatively calm on the streets of Xinjiang now," he said.

The manager's company, which sells make-up and other cosmetic products online, is one of many that have had to relocate staff outside of Xinjiang to continue operations, he said.

The owner of another online store, which sells dried fruits, nuts and other snacks, said she did not know of any regional network in Xinjiang. Most of the store owner's staff remain in neighboring Gansu province, she said.

China has given little sign of when it will lift the Internet restrictions but said it will gradually do so as Xinjiang stabilizes.