The work, the first since the road to the mountain's Base Camp was built in 1978, had seen the road surface made even, the road base widened, and the bends fenced by guardrails, the vice chairman of Tibet Autonomous Region Hao Peng said.

"Driving used to be very dangerous on the mountain road with more than 170 curves, but that's in the past now," Hao was quoted as saying by Xinhua news agency in a report from Lhasa, Tibet's capital.

With a length of 110 km and a 3.5-meter-wide road surface, the highway starts from the national highway 318 inside Tingri, Xigaze Prefecture, and ends at Rongpu Monastery near the Base Camp at the foot of the mountain.

Hao said the regional government planned a second stage of improvements in which the sand and stone road would be sealed with asphalt.

"But the plan is subject to a feasibility study and environment assessment before it is approved by the central government. That will probably take a pretty long time," he said.

Hao reiterated a denial that the regional government planned to build other tourist facilities, such as hotels, at the Base Camp and denied that a whole new road was planned on the mountain.

A Tibetan tourist bus driver said the repairs had cut bus travel times in half from the previous average of four hours.

Earlier, many world environmental groups and non-governmental organisations had expressed concern over China's plans to upgrade the existing road to Mt Everest, saying such a move would attract more tourists to the fragile Himalayan region and lead to increased pollution and environmental damage.

But, chief of the administration for Mt. Everest State-Level Nature Reserve Gama said the improvements would help protect and preserve the vulnerable plateau ecosystem.

"Before the repairs, the road surface was bumpy and unsafe, many drivers shunned the highway and would drive their vehicles off road, which destroyed the vegetation," he said.

The director of agriculture and animal husbandry department of Tingri County Dawa said the repaired highway would play a role in helping raise income of local farmers and herders, and in facilitating their out-bound trips to seek employment.

Organizers of the Beijing Olympic Games have ambitious plans for the longest torch relay in Olympic history – a 137,000-km, 130-day route that would cross five continents and scale Mt Everest (Qomolangma in Chinese), which straddles the border between China and Nepal.