Below is an article published by ABC News:

For a fifth straight year, China plans to close Tibet to foreign travelers during a sensitive period starting in mid-February, travel agents said Thursday [19 January 2012].

Agent Yu Zhi of the Lhasa Youth Tourist Agency said Thursday the government's tourist administration in Tibet's capital had informed agents that foreign travelers would be banned from Feb. 20 to March 30.

Another agent with the China International Travel Agency in Lhasa, who wouldn't give her name, said she'd been told the ban would end March 20.

The periodic closure of the Himalayan region encompasses the Feb. 22-24 Tibetan new year festival of Losar as well as the anniversary of a deadly anti-government riot among Tibetans on March 14, 2008.

Tensions are especially high this year following the self-immolations of at least 16 Buddhist monks, nuns and other Tibetans. Most have chanted for Tibetan freedom and the return of their spiritual leader, the Dalai Lama, who fled to India amid an abortive uprising against Chinese rule in 1959.

While authorities have never explained the rational behind the annual closure, it's seen as a standard measure based on the assumption that outsiders could either inspire or witness renewed anti-government protests or other conflicts.

"We haven't seen a written notice, but it's the same as previous bans. We were not told about the reasons, but it's probably because of the Tibetan new year," said Yu, the Lhasa agent.

In addition to the coming closure of Tibet proper, traditionally Tibetan areas of Sichuan province and other parts of western China where most of the self-immolations have taken place have been closed to outsiders for months amid a massive security presence.

A clerk with the Lhasa Tourist Bureau denied there was a ban, but declined give her name. Chinese officials often issue orders regarding sensitive political issues only verbally to allow deniability and maintain the impression of control.

Although Chinese citizens are generally exempt from such closure orders, they have dented China's hopes to develop tourism into a major economic driver in one of the country's poorest regions. Many Tibetans resent Beijing's heavy-handed rule and large-scale migration of China's ethnic Han majority to the Himalayan region. While China claims Tibet has been under its rule for centuries, many Tibetans say the region was functionally independent for most of that time.