Chinese authorities have closed Tibet to foreign visitors, travel agents said this week, just 10 days after two Tibetans set themselves on fire in the troubled region.
The move comes at the start of a festival that traditionally sees tourists flock to the Himalayan region, which has been under tight security since riots against Chinese rule erupted in the Tibetan capital of Lhasa in March 2008.
Major travel agencies said they were told by Tibetan tourism authorities in late May that travellers from overseas would not be allowed into the vast, remote region and said they were clueless about how long the ban would last.
"The tourism bureau asked us to stop organising foreign groups to Tibet in late May. We don't know when they will lift the ban," an employee at the Tibet China International Tour Service told AFP.
While the official reason for the ban was not immediately clear, one agent said it could be linked to the Saga Dawa festival, which celebrates the birth of Buddha in the Tibetan calendar.
"It was halted in late May. People said it was because of the... festival," an employee at the Tibet China Travel Service said.
The festival traditionally sees Buddhist pilgrims flock to Tibet to mark the month-long celebration, which began on June 4 this year - a date that coincided with the anniversary of the 1989 Tiananmen crackdown on democracy protests.
Another agent from the Tibet China Youth Tour Service said the ban might also be linked to the "recent social order problem".
Not the first travel ban
China sporadically bans foreign travel to Tibet, where many Tibetans complain of cultural and religious repression at the hands of Chinese authorities - a claim the government denies.
Since March last year, 37 people have set themselves on fire in Tibetan-inhabited areas of China in protest at repressive government policies, according to activists.
On May 27, two Tibetan men set themselves alight in front of the Jokhang temple, a renowned centre for Buddhist pilgrimage in the centre of Lhasa - the first such incident to hit the regional capital.
Foreign tourists were banned from travelling to the region for more than a year in 2008 after anti-government riots erupted in Lhasa - unrest that subsequently spread to other Tibetan-inhabited areas of China.
Even in normal times, overseas tourists need special permits to travel to the remote region as well as their visas for China, and have to travel in tour groups.