Potala Palace in Lhasa

Ahead of the 90th anniversary of the Chinese Communist Party on July 1, China has closed off the former forbidden kingdom of Tibet to foreign tourists, travel agents said on Thursday.

Many ethic Tibetans have chafed under Chinese rule and China is sensitive to instability or any other perceived threat to their one-party rule.  The autonomous region of Tibet, with its ethnic minorities, has been a constant thorn in China's side.

It's a new rule because of the 90th anniversary celebration, a travel agent at a major Western hotel in Tibet's capital Lhasa told Reuters, requesting anonymity. Even with a tour group, foreigners cannot come.

A Beijing-based travel agency said it was notified months ago that foreigners would not be allowed in Tibet during July but hoped that the restriction would be eased in time for important Tibetan festivals in August.  They also complained that they were losing a lot of money and just had to tell their clients sorry.

Ren Zhiwei of Tibet China Travel Service and Zeng Meimei of Tibet China International Travel Service, both in Lhasa, said Thursday that Chinese tourists are not affected by the ban.

Foreigners have always needed permission to travel to Tibet, but the government periodically puts Tibetan areas out of bounds.  Tibet has been closed intermittently to foreign tourists since deadly anti-government protests there in 2008.  In April, the government forbade foreigners from ethnically Tibetan parts of neighboring Sichuan province, where exiled Tibetans and activists allege that authorities locked down a Tibetan Buddhist monastery when a young monk burned himself to death.

Chinese troops marched into Tibet in 1950, forcing their spiritual leader, the Dalai Lama, into exile in India nine years later.  While many Tibetans dislike Beijing's rule and the influx of Han Chinese diluting their population, Tibet's Chinese-appointed governor, Padma Choling pointed to 18 years of double-digit economic growth ahead of the 60th anniversary of Chinese rule over the region last month.   She claimed that Chinese rule had rescued Tibet from thousands of years of feudal serfdom.