China has tightened restrictions on travel by foreigners in the restive Himalayan region of Tibet after five American activists unfurled a banner at the foot of Mount Everest to protest against the staging of the 2008 Olympics in Beijing.

The new rules came into effect after the week-long May Day holiday, according to an official with the state-run China Travel Service in Lhasa, the Tibetan capital.

She said: “We can’t let foreign tourists just go anywhere by themselves. In the past they could be left alone to travel independently as they wanted for a few days. Now this is not allowed any more.”

The restrictions will also stop foreigners applying for a permit to enter the region from the office of the Tibetan travel bureau in the southwestern city of Chengdu, from where there are direct flights to Lhasa. All travel must now be approved by the head office in Lhasa, which operates under police supervision.

The official added: “Management is tighter because of the Americans on Everest. All permits must be issued here in Lhasa.”

The rules are similar to those that existed in the early 1990s when the entire region was effectively closed to foreigners, except for a tiny number of officially organised tour groups. That crackdown was prompted by a series of violent demonstrations, mostly led by Tibetan monks, against Chinese rule and by the imposition of martial rule after riots that swept Lhasa in the late 1980s.

There has been a gradual easing of restrictions in recent years although Tibet remains the only region of China where all foreign tourists must obtain a travel permit to gain entry.

Recently it had been simpler for tourists to pick up the permits in cities such as Chengdu and Zhongdian near the Tibetan border before boarding a plane or hiring a vehicle, or in Beijing and Golmud - now on the railway line to Lhasa that opened less than a year ago.

Tibetan authorities had hoped that the new train service would boost tourism. But the new rules could cool the enthusiasm of foreign tourists if they are limited to visiting Lhasa and are then forced to complete complex procedures in order to leave the city, even as part of a tour group.

The five Americans were detained at the Chinese base camp for Everest last month. They were protesting against plans to carry the Olympic torch to the summit of the world’s highest mountain en route to the opening of the Games in Beijing on August 8 next year.

Their banner read: "One World, One Dream, Free Tibet 2008", a play on the official slogan of the Games "One World, One Dream". After their arrest they were expelled from the country.

Robert Barnett, a Tibet expert at Columbia University, said: “It may seem strange if five students with a camera can have such an impact on Chinese policy. But in fact restrictions have been increasing in Tibet over the last year, with intensified campaigns against 'the Dalai', renewed bans on religion for all officials, and recently public warnings about ‘western hostile forces’.

“I think that the issue with these US students was not so much that they staged a protest in Tibet, but that they staged it in the middle of a rehearsal for the Olympic ceremonies. The fear of embarrassment during the Olympics seems to be increasingly a paramount concern for officials.”

Beijing has long been nervous of campaigners in Tibet and from overseas, who argue that the devoutly Buddhist region, where most people pledge loyalty to the exiled Dalai Lama, is not a part of China.

Lhasa first opened to foreign tourists in the mid-1980s and quickly became an alternative destination for young backpackers seeking a more exotic destination after visiting Kathmandu. When a riot erupted in Lhasa in September 1988, the Chinese authorities accused the numerous foreigners staying in the city of stirring up anti-Chinese feeling and said that they had been involved in the demonstrations by ethnic Tibetans. Travel restrictions were imposed at once, effectively closing off Tibet for several years.

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