Himalayan glaciers are melting faster than any other body of ice as a result of climate change, threatening devastating consequences to the livelihoods of millions of people dependent on the river Ganges, the Nepalese government has warned.

Speaking at a two-day Himalayan climate change conference in Kathmandu, Madhav Kumar, Nepal’s prime minister, said: “The Himalayan glaciers are retreating faster than any other glaciers in the world as the temperature is increasing.”

“The potentially catastrophic impact on lives and livelihoods has assumed a huge importance in our international relations,” he added.

The Nepali leader’s comments, intended to raise the mountain republic’s concerns ahead of the UN climate change talks in Copenhagen in December, contradict those of top officials from neighbouring India.

Jairam Ramesh, India’s environment minister, has disputed evidence showing that climate change is hastening the retreat of Himalayan glaciers. He has argued that in some cases glaciers are growing.

Senior Indian hydrologists say the retreat of glaciers is far from catastrophic and that they would take several hundred years to disappear. Some of the quickest melting is taking place in Europe rather than the Himalayas, according to the Swiss-based World Glacier Monitoring Service.

The consequences of depleted glaciers would be dire. Seven of the world’s greatest rivers, including the Ganges, Indus and Mekong, are fed by the glaciers of the Himalayas and Tibet. They supply water to about 40 per cent of the world’s population.

“The impacts of climate change on the Himalayas - the water tower of South Asia - are already affecting the lives of millions of people across south Asia,” said Kunio Senga, the director-general of the Asian Development Bank’s south Asia unit. “Droughts, floods and landslides are increasing in frequency and intensity.”

Water supply is likely to become an increasing priority for both India and China as they seek to maintain high economic growth rates and sustain large populations dependent on farming.

“This region is also amongst the most vulnerable to climate change. So what happens here truly matters and must be of global concern,” said George Verghese, a visiting professor at the Centre for Policy Research in New Delhi. “River basins do not recognise national boundaries. Nations within these international river regimes – Afghanistan, Pakistan, Nepal, Bhutan, India and Bangladesh in this case – must co-operate or risk dire consequences from which they might not easily recover.”

Prof Verghese said the development of water resources in the region were a litany of missed opportunities and called on India to reach out to China in discussions about the region’s water use.

“[Countries in this region] have lost an inordinate amount of time in seizing the great opportunities [from their water resources] that stare them in the face. Mounting social pressures, impatient populations and climate change now demand meaningful action, overcoming past prejudices,” he said.

Mr Madhav’s concerns are shared by Nepali parliamentarians, who warn that the future of the young republic which has emerged from a decade of civil war is jeopardised by very visible changes to the snow-capped landscape and increasing hardship for mountain pastoralists. Nepal alone has more than 3,000 glaciers.

“If we don’t consider the impact of climate change, the dream of a new Nepal which is carried by millions of Nepalis will be shattered, [making it] short lived or impossible,” said Gagan Thapa, a youth leader of the Nepali Congress.