Apartment buildings are seen under construction at the foot of mountains in Lhasa, capital of Tibet Autonomous Region in Southwest China, in this photo taken on April 10, 2007. The Qinghai-Tibet Railway has boosted Tibet's development, and the central government will further invest 77.8 billion yuan in infrastructures in this region before 2010. [Xinhua]

UNESCO disagrees and has expressed concern at the palace becoming increasingly hemmed in by nondescript modern Chinese buildings.

"Seeing is believing. I hope the UNESCO officials can carry out an on-the-spot investigation of the Potala Palace. A conclusion without an investigation is meaningless," said Qiangba Gesang, palace director for 19 years.

A year after its inauguration, the Qinghai-Tibet railway has transported 1.5 million passengers into Tibet, nearly half of the total tourists arrivals in the region. Concerns have arisen that the weight of the tourist influx would pose a serious impact on the mud and wood structures of the 13-storey palace.

"For the overcrowding of tourists, we have found solutions," said Qiangba Gesang.

The palace currently restricts visitors to 2,300 a day and stays open from 7:30 a.m. to 6:30 p.m.

"The restriction of visitors proves our commitment to the protection of Potala Palace," said Qiangba Gesang. "We can't fully satisfy the needs of all tourists, but we have no other way around it."

Qiangba Gesang said the central government has kept a close eye on the preservation of Potala Palace, which was added to the list of world cultural heritage sites by UNESCO in 1994.

In 2002, the central government invested a total 179.3 million yuan (about 23.6 million U.S. dollars) in the renovation of the palace and plan to invest more in the near future, he said.

Potala Palace, the essence of ancient Tibetan architectural art, was first built by the Tibetan King Songtsa Gambo in the 7th century during the Tang Dynasty (AD 618-907), and was extended during the 17th century by the Dalai Lama.

The palace, together with the Norbu Lingka and the Sakya Monastery, are the three main Tibetan cultural heritage sites.

The local government will invest 140 million yuan (about 18.4 million U.S. dollars) to renovate the areas surrounding Norbu Lingka, the summer palace of the Dalai Lama.