China's easing of a ban on the popular online encyclopedia Wikipedia appears to have been short-lived.

Users reported Friday that the site was unavailable in several parts of China, barely a week after it suddenly became accessible.

It wasn't immediately clear if user-contributed encyclopedia was unreachable due to technical glitches or because government censors had blocked the site again.

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The Foreign Ministry and Ministry of Information Industry did not immediately respond when contacted for comment Friday.

Beijing first blocked access to the English and Chinese versions of Wikipedia in October last year, apparently out of concern about entries touching on Tibet, Taiwan and other sensitive topics.

China's communist government has waged a battle to control the anarchic Internet and filter the information Chinese can get.

Police employ an array of measures, from sophisticated filters and detection software that hunts for sensitive words to having officers monitor Web traffic.

As a result, surfing the Web in China is a very different experience from that in much of the world.

Because almost anyone can add to and edit listings in Wikipedia, the site is famously freewheeling, addressing sensitive topics that pose a challenge to Beijing's control.

The site's English version was unblocked last month, while the Chinese version became available late last week, until Friday when users said both versions could not be accessed.

"China's Internet users are not different from other countries' users," said Yuan Mingli, 33, a software engineer in Shanghai who has contributed articles on computer science and Chinese historical figures to the site. "Wikipedia is a very important source of information for us."

Experts had earlier expressed skepticism over the government's unannounced lifting of the ban on the popular site, saying it could be only temporary.

"It's great to see Wikipedia unblocked, though in China an unblocking is probationary: it might be blocked again in a day, a week, or a month," Jonathan Zittrain, professor of Internet governance and regulation at Oxford University, said at the time.

Wikipedia contributors such as Yuan said they recalled at least two instances before the ban when censors teased Internet users by sporadically blocking access to the site for weeks at a time.

It was also not clear why Beijing had earlier allowed access to the site.

Chinese Foreign Ministry spokeswoman Jiang Yu said Thursday she had no information on the issue, but added China "actively supports and promotes the development of the Internet."

"We manage the Internet in accordance with our laws and regulations," Jiang said.