Carrying the Olympic flame to the summit of Everest live on television is, even by Chinese standards, a demanding challenge.

This week mountaineering authorities in Lhasa announced they wanted to limit the number of foreign climbers on the Tibetan side of the 8,850 metre (29,035ft) peak in spring 2007 to allow a trial run to assess the technology and manpower needed to start the Beijing Olympics from the summit of the world.

But the propaganda value has been severely compromised by video footage taken by a western mountaineer of a 17-year-old Tibetan nun being shot in the back by Chinese border guards as they tried to stop a group of 73 refugees crossing the Nangpa La, a 5,800 metre pass 15 miles west of Everest, to Nepal.

The nun was Kelsang Namtso from Nagchu prefecture, the only daughter in a family of six. Like many Tibetans, she had no access to education and planned to study at the Dolma Ling nunnery in India. Travelling with her childhood friend Dolma Palkyi, she endured high winds and deep snow. The two young women ran out of food as they approached the difficult pass.

The trail to the Nangpa La pass is overlooked by the base camp of the 8,200 metre mountain Cho Oyu, often used as a training peak by climbers gaining experience for an attempt on Everest. Footage of People's Armed Police (PAP) taking aim at refugees and of bodies hitting the snow was taken by Romanian mountaineer Sergiu Matei and broadcast around the world.

A death has been reported by the Chinese state news agency Xinhua, but it did not name the victim and claimed PAP opened fire in self-defence.

Mary Beth Markey of the International Campaign for Tibet (ICT) said: "We don't know if the targeting of this group was an isolated incident by Chinese border police or represents hardline protocols."

The appointment of hardliner Zhang Qingli as party secretary of the Tibet Autonomous Region (TAR) in May has signalled a renewed determination by Beijing to cement the region to China. Chinese migration into Tibet has accelerated with the opening of the new high-altitude railway to Lhasa.

Restrictions on religious freedoms in the TAR have been tightened in what Mr Zhang called a "fight to the death struggle" against the Dalai Lama in a speech in May. Patriotic re-education in nunneries and monasteries has driven more nuns and monks to face the dangers of the Nangpa La to escape Tibet.

Most refugees travel in autumn and winter when deep snow reduces the chance of meeting border patrols, but conditions are severe. Palkyi, 16, claimed she had paid $700 (£370) to smugglers who guide groups over the Himalaya mountains. Western tourists attempting to climb Cho Oyu frequently encounter refugees and there have been several reports of violence in recent years.

ICT's director, John Ackerly, himself a mountaineer, says climbers should be bolder in criticising human rights abuses.

"You can compare it to our responsibility to help an injured fellow climber on the mountain," he said. "It's a basic human concern for another individual. Obviously there are choices and things you need to balance. It's not an easy decision all the time, but sometimes, as in this instance, it's no skin off anyone's back to speak out. People think that China holds a much more rigorous list than they do."

Changes in regulations on Everest are also being seen as a response to criticism in the spring that the low cost of climbing the mountain from Tibet caused accidents, including the death of British mountaineer David Sharp in May. Although reports that fellow climbers ignored the dying Sharp proved false, mountain guides say independent climbers operating on a shoestring are relying too heavily on the resources of others.

So China is making it more expensive to climb Everest, as well as limiting numbers during the run up to the Olympics. It will also require climbers going to Everest to have previous experience of climbing another mountain of more than 8,000 metres.

So far, China has not changed its comparatively light regulations on communications equipment such as satellite phones. That may change. With the Olympics drawing closer, China may decide it doesn't need more negative publicity from incidents such as the death of a young nun.

· Ed Douglas is a mountaineer and writer on climbing.

The exodus

· Mountain border crossings, such as the one attempted by nun Kelsang Namtso, whose body is pictured above, are risky and expensive.

· China invaded Tibet in 1950 and claims sovereignty over the Himalayan region. Tibetans pledge allegiance only to the Dalai Lama.

· The Dalai Lama fled to India in 1959 after a failed uprising during which monasteries were destroyed.

· Each year between 2,500 and 4,000 Tibetans attempt to cross the Himalayas to reach India via Nepal.

· The Indian embassy in Kathmandu, Nepal, issues up to 30 travel documents a day to Tibetan refugees.

Luc Torres