It is being billed as the ultimate trek, a thigh-busting 157-day walk over the spine of Nepal's mighty Himalayan range that will take its participants to some of the most remote spots on the planet.

From next year, adventurers seeking to push themselves to their limits will be able to take part in the first guided walk along the Nepal section of the Great Himalayan Trail.

The 1,700-kilometre (1,050-mile) trek, which kicks off in February 2011, is being run by World Expeditions, a global adventure travel company that has been taking trekkers to Nepal for more than three decades.

But the trailblazer is British trekker Robin Boustead, who has spent much of the last decade trying to put together a viable walking route across the top of the world.

Last year Boustead finally completed the arduous walk along the length of Nepal's Himalayas, fulfilling a long-held ambition to forge a viable route through the mountains.

"Asia is the only continent that does not have a long-distance walking trail and so it seemed an obvious choice - everyone on the planet has heard of the Himalayas," said Boustead in an interview with AFP.

"I first came across the idea in 1993 and fell in love with it. But it was not until Nepal demilitarised its border with China in 2002 that it became viable."

Boustead lost 20 percent of his body weight over the course of his marathon walk, which took him from Kanchenjunga on Nepal's eastern border with Tibet to the impoverished western region of Humla.

En route, he encountered the huge variety of cultures to which Nepal is home, from the mainly Buddhist Tamang people of the central Langtang region to the far west, where ancient animist practices mix with Hinduism.

He walked only on trails that were already in use, from ancient trade routes to paths used for centuries by farmers transporting livestock, relying on local guides to show him the way.

Boustead will lead part of the World Expeditions trail, which begins in February 2011, costs 31,000 dollars and will take 157 days to complete, although it can also be broken down into seven smaller stages.

"So far one person has signed up to do the whole thing and a handful of others for individual sections," said Brad Atwal, manager in Britain for World Expeditions.

"Our clients tend to be professionals aged 40 and over who have the money and time to do this kind of thing. And they will have to be fairly experienced, it's definitely not a first-time trek."

Some of the sections will require mountaineering ability because of altitudes of more than 6,000 metres (20,000 feet) and the need for ice axes and crampons.

Top mountaineers including Stephen Venables, the first Briton to climb Mount Everest without supplementary oxygen, have been recruited to lead the more difficult sections of the trail.

Launching the trail commercially is a major logistical undertaking - many of the areas it passes through are untouched by tourism.

But Boustead believes that trekkers who head straight for the well-publicised Everest and Annapurna regions are missing out and he hopes the trail will spread the benefits of tourism across a much broader area of Nepal.

"People come to Nepal because of the mountains. The hope is that they will come back because of the people," he said.

"But if you only go to the very touristy areas like Everest and Annapurna, you don't get the close personal contact that you would outside of those places."

Britain's Department for International Development has pledged around three million dollars to promote the trail and help local communities capitalise on the hoped-for influx of visitors.

The idea of a Great Himalayan Trail is not new - as far back as 1980, the Indian army carried out a series of treks from Mount Kanchenjunga on Nepal's eastern border with China to the Indian state of Ladakh.

At that time huge swathes of the Nepalese Himalayas, including the former kingdom of Mustang on the border with Tibet, were closed to outsiders.

A Maoist insurgency that began in 1996 also put large parts of rural Nepal off limits for foreign visitors and it was not until the signing of the peace agreement in 2006 that the idea became a practical possibility.

Ultimately, Boustead hopes it will be possible to walk the entire length of the Himalayas, from China in the east to Afghanistan in the west.

He is researching routes through Bhutan and the Indian state of Arunachal Pradesh, and next year hopes to travel to Pakistan and Afghanistan.