As global warming and deforestation accelerated, and technology made wild places accessible, environmental and social pressures on the remotest regions were mounting, said the authors from the World Conservation monitoring centre in Cambridge.

They found that many mountainous regions - officially inhabited by one in five of the population, according to the UN, were barely recognisable when compared with 60 years ago, mostly because forests had been felled to make way for cattle grazing and agriculture.

Almost half of Africa's upland areas had been put under the plough or the hoof, and been made susceptible to fire and human conflict.

This land use change, said the report, had increased rapidly with globalisation. It was adversely affecting soils, regional climates, and water supplies for lowland areas. If trends continued, said the report, the fabled snows of Kilimanjaro in east Africa would have all melted within 30 years.

Greenland's icy mountains were expected to be the region hardest hit by global warming. The authors expected 98% of its mountain areas to experience severe climate change by 2055.

"These losses are not just regrettable but actually threaten the health and well-being of us all. Mountains are the water towers of the world, from where the world's rivers spring. We must act to conserve them for the benefit of mountain people, for the benefit of humankind," said Klaus Toepfer, head of the UN's environment programme, yesterday.

The report also found that more than 40% of the world's mountain regions had experienced violent conflict since 1945, compared to 26% of lowland areas. In Africa 67% of the mountainous land had suffered "high intensity conflict".

"Mountains give strategic advantage to insurgents by providing places of refuge. The terrain hinders road building, thereby restricting law enforcement. A lack of infrastructure can make civil war more likely or prolonged," said Adrian Newton, lead author of the report.

Mr Newton questioned the land use policies of many countries, which encouraged intensification of agriculture in mountain regions. "These lands are less suitable for growing crops than more lowland areas. This, allied to environmental degradation, may play a role in increasing the risk of armed conflict," he said.

Biological losses were expected by the report to be heavy. The mountains of Europe, parts of California and the north-west Andes, were among the most threatened, bio-diversity rich, mountain areas in the world, it said, and should be made conservation priorities.

Mankind could be expected to deliberately destroy great areas over the next 30 years. A quarter of all mountain areas could be "highly impacted" by infrastructure development such as roads, mining, and power and pipelines by 2035.

The UN is anxious to raise attention to the problems facing mountain areas because they are inhabited by some of the most vulnerable people, who can lose their livelihoods with even the smallest shifts in climate or insensitive developments.

Meanwhile, many mountain regions are losing people. Thousands of villages in Europe are deserted most of the year; in other areas like Nepal, people are drifting to the cities in search of work.

"These losses affect us all, said Mr Toepfer. "Mountains have been a source of wonder and inspiration for human societies and cultures since time immemorial. But some of these last wild areas are fast disappearing in the face of agriculture, infrastructure development, and other creeping impacts".

The report will be presented to heads of state at the world's first mountain summit at Bishkek in Kyrgyzstan next week.

At risk: a way of life

· South America's mountain areas are vulnerable to major earthquakes - with approximately 88% of the land deemed at risk.

· As glaciers retreat many new lakes are formed which could burst their banks and endanger millions of people.

· One in four remote mountainous regions may soon be affected by new roads, mining and power and pipeline schemes.

· More than one in four of the world's 6,000 endangered languages are from mountainous regions.