<< Potala Palace in Lhasa, a world heritage site, is under particular pressure from 'high impact' tourism, critics say.

Four million tourists visited the thinly populated Himalayan region of 2.8 million people in 2007, China's state news agency Xinhua reported yesterday.

"This is the first time that the number of tourist arrivals exceeded the total population," said Matt Whitticase, of the Free Tibet Campaign. "Tourism is obviously a pillar of China's western development strategy but it is putting unacceptable strains on Tibet's fragile environment."

Despite the construction of airports and a rail link from the capital, Lhasa, to Xining in neighbouring Qinghai province, Tibet's tourist sector ran 775 tour buses to cope with the influx, Xinhua said. The rail link, which opened in 2006, cuts across nearly 1,250 miles of rugged plateaus and high-altitude permafrost and carries more than 11.5 million tourists into Tibet a year, as well as around three-quarters of total freight in and out of the region.

Last year, a third civil airport was built in Nyingchi, and a fourth is planned in Nagari, which will be the highest in the world.

Local authorities said that tourism would generate about 4.8bn yuan (£340m) for the whole of 2007, up 73% from the previous year, but that is a fraction of the potential. The number of tourists is still less than a 10th of those visiting the province of Yunnan on Tibet's southern border, officials say.

Tourism already accounts for about 9% of Tibet's gross domestic product, and exploiting the region's cultural allure is the cornerstone of government efforts to integrate Tibet with China and stimulate the region's primarily rural economy.

The government says the tourist surge will also help to generate the income necessary to protect Tibet's ancient monuments and ways of life. But Whitticase said the Tibetans themselves were not benefiting. "Tibetans are being left behind and the tourist industry is being run by Han Chinese companies not domiciled in Tibet," he said.

There are concerns that the region's culture is being "swamped" by China's majority Han population. The Dalai Lama, Tibet's exiled spiritual leader, has accused the Chinese government of committing "cultural genocide", and warned that the fragile environment of Tibet is being put under threat, causing problems not just in Tibet, but in India, Bangladesh and China itself, which depend on the Himalayan plateaus for their water supplies.

Critics also say that China has not taken into consideration the infrastructure required to support the huge number of visitors. It has also concentrated on "high-impact tourism", Whitticase said, with millions descending on a few attractions, including Lhasa's Potala palace, which is surrounded by traffic and urban sprawl.