Record numbers of climbers are expected to try to reach the peak of Everest this spring.

Mountaineering agencies in Nepal say about 40 teams have applied for permission to climb the world's highest mountain from April to May - which is regarded as one of the best times of year.

Last year, 37 teams tried to scale the peak; 24 made it to the top, at 8,848m (29,028ft) - or 8,850m (29,035ft) according to the latest measurement.

The surge in demand has led to concerns over the safety of expeditions. Critics say the side of the mountain at peak seasons resembles a human conveyor belt.

Inexperience

Campaigners say that Western mountaineering companies take poorly trained or inexperienced climbers onto Everest.

Figures released by the Nepalese authorities show that around one in 10 people are killed making the attempt.

On one occasion in 1996, 12 people died on the mountain because of over-crowding and queuing on the most popular route, the south-east ridge, which coincided with atrocious weather.

Environmentalists have also complained that the expeditions leave large amounts of litter and debris on the mountain.

But the government is now trying to ensure that the climbers remove any discarded equipment - such as empty oxygen cylinders.

The authorities say mountaineers will have to prove they have the necessary equipment to take discarded items back home with them.

BBC South Asia analyst Alastair Lawson says that with mountaineers sometimes spending more than $50,000 to try to climb Everest, expeditions are a large source of revenue for the Nepalese authorities.

Millennium milestone

The first attempt to climb Everest in the new millennium was aborted last month, when a Sherpa guide on an expedition fell ill.

A four-member Canadian team arrived in the Nepalese capital Kathmandu on Friday to attempt to scale the mountain's northern, Tibetan side.

"It would be fantastic to reach the top in the new millennium," expedition leader Francois Loubert told Reuters news agency.

A six-member team, which arrives on 10 March, is expected to be the first this season to attempt the peak from the southern, Nepalese side.

By the end of March, climbers from all over the world are expected to be in Kathmandu for Everest attempts, including a four-member team of women Sherpas.

More than 550 climbers from more than 20 countries have reached the summit.

In recent years the number of teenagers, women and climbers without oxygen on Everest has soared.