Russell Brice, a New Zealander and leading Himalayan expedition organiser, said he had called off plans to send clients up the Tibetan side of the world's highest peak and that other teams were also cancelling.

"I cancelled my expedition three days ago. I think most people on the north side are cancelling and some are trying to shift to the south side" of the mountain in Nepal, he told AFP from his office in the French Alps.

He said his 16 clients this year, who pay tens of thousands of dollars each to try to reach the top of the world, "have taken time off work, been training, got themselves mentally prepared -- so it's a huge blow for them."

Organisers hoping to send climbers up the north side of the 8,848-metre (29,028-feet) mountain have in recent months been grappling with uncertainty over whether the mountain will even be open.

Earlier this year, China said it would closely vet prospective foreign climbers applying for a permit.

China plans to send the Olympic torch to the summit of Everest in early May, and sources in the mountaineering community said Beijing was eager to keep pro-Tibet protestors away -- especially while the torch is in the area.

Brice said he was cancelling because he had not yet received his licence.

In addition, Tibet -- including access to the north side of the peak -- has been closed off indefinitely to foreigners following a wave of unrest there last week and amid a major security clampdown.

Brice said he had unable to guarantee to clients that they would be allowed in when the trek to base camp on the Tibetan side of the mountain is due to start early next month.

"It's very difficult to find out what's going on, to find out what is true and what is a rumour," he said.

"We can't blame the China Tibet Mountaineering Association because there are factors involved that are way beyond their control," he added.

Brice also said his company was also supposed to be fixing kilometres (miles) of ropes on the mountain this season for several other expeditions, including the Chinese Olympic torch climb.

"I was supposed to be laying out the ropes that will be used by expeditions including the Chinese one, but have not been given a permit," he said.

That huge logistics operation -- usually carried out by teams of hardened Nepali and Tibetan sherpas -- has also been called off, meaning Chinese authorities will have to arrange the roping of the mountain themselves.

He said other mountaineering agencies "might try and shift their expeditions to the south side, but other people are worried about overloading on the south side" in Nepal.

On the southern approach, expedition organisers are confused as while the Nepal government insists the restrictions do not apply to Nepal, the country is coming under Chinese pressure to keep the mountain clear and is also refusing to issue permits.

"Leaders and western guides from three expeditions are already here and we don't know what to tell them," said Ishwori Poudel, who runs an expedition firm and has 55 foreign climbers waiting to find out if they can attempt Everest.

First summitted in 1953 by Edmund Hillary and Tenzing Norgay, Everest has since been summitted at least 3,000 times, and the mountain usually sees dozens of commercial expeditions annually that bring in millions of dollars to Nepal and Tibet.

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