Dozens of Sherpa guides packed up their tents and left Mount Everest's base camp Wednesday, after the avalanche deaths of 16 of their colleagues exposed an undercurrent of resentment by Sherpas over their pay, treatment and benefits.

With the entire climbing season increasingly thrown into doubt, the government quickly announced that top tourism officials would fly to base camp Thursday to negotiate with the Sherpas and encourage them to return to work.

But while Nepal's government has been heavily criticized for not doing enough for the Sherpas in the wake of last week's disaster, the deadliest ever on the mountain, one top official blamed the walkout on "hooligans."

"It was crowd behaviour — some hooligans were creating problems, but things are getting back to normal," said Sushil Ghimire, secretary of Nepal's Tourism Ministry. He and other top officials were to fly by helicopter Thursday to base camp.

The Nepal Mountaineering Association said it has not received any confirmation regarding the "abandon of the expeditions" and that whatever news "disseminated in the media about the abandon of the expedition is false and does not any hold any sense." 

"Yes, Nepalese mountaineers are in deep sorrow after the huge human loss and they are trying to cope with the situation," president Ang Tshering Sherpa wrote in an email. "They are trying to be mentally prepared for the expedition and it will take some time to return in the normal situation."

While it was unclear just how many of the 400 or so Sherpas on the mountain had joined the walkout, a number of expedition companies have already cancelled their climbs, and the lucrative climbing season is in disarray. Most attempts to reach Everest's summit are made in mid-May, when a brief window normally offers better weather.

Equipment loaded into helicopter

Without the help of the Sherpas, who are key guides and also haul tons of gear up the mountain, it would be nearly impossible for climbers to scale the mountain. Many climbers will have to forfeit most or all of the money they have spent to go up Everest — at a cost of $75,000 or more.

"It is just impossible for many of us to continue climbing while there are three of our friends buried in the snow," said Dorje Sherpa, an experienced Everest guide from the tiny Himalayan community that has become famous for its high-altitude skills and endurance.

Thirteen bodies were recovered after the avalanche. Three Sherpas were still missing in the ice and snow, and are presumed dead.

'It is just impossible for many of us to continue climbing while there are three of our friends buried in the snow.'- Dorje Sherpa, Everest guide

"I can't imagine stepping over them," Dorje Sherpa said of the three guides.

American climber Ed Marzec, 67, said by phone from base camp that Sherpas were loading their equipment onto a helicopter.

"There are a lot of Sherpas leaving this morning, and in the next two days there will be a huge number that will follow," said Marzec, 67, who is from California. He said he had already decided to abandon his climb.

But Marzec said some smaller companies were hoping to go ahead with their summit attempts.

Tusli Gurung, a guide who was at base camp Wednesday, estimated that nearly half the Sherpas had left.

Expeditions cancelled

Seattle-based Alpine Ascents International announced it was calling off its expedition. "We have all agreed the best thing is to not continue this season's climb, so that all can mourn the loss of family, friends and comrades in this unprecedented tragedy," the company said on its website.

New Zealand-based Adventure Consultants also said it was cancelling its expedition.

International Mountain Guides, the largest expedition on Everest, said Wednesday afternoon it is forced to end its climb as well, "due to perilous conditions" resulting from the avalanche.

"The Icefall route is currently unsafe for climbing without repairs by the Icefall doctors, who will not be able to resume their work this season," IMG director Eric Simonson wrote on the company's website. "We have explored every option and can find no way to safely continue the expedition."

IMG climbers will descend over the next few days and join teams from other cancelled expedition, Simonson wrote. 

While these expedition teams cite safety concerns for pulling out, others are more vocal about the political impetus preventing them from moving forward.

The owner of Canada-based Peak Freaks Expeditions said there is anger developing on Everest.

"There is talk of retaliation on Sherpas who want to continue and I'm not about to be part of this or put any of my staff or clients in danger," Tim Rippel said. "There seems to be two tribes forming and this makes for a dangerous situation in an already unstable mountainous environment. If we care about our Sherpa families as so many say they do, then we must give peace a chance."

"It's gotten too messy," he continued. "We hung in here to see if we could learn from all of this and be of assistance in anyway through this crisis, but now that we have an army, police and angry Sherpas staging at base camp, it's time to go home."

Ice the size of office buildings

Friday's avalanche was triggered when a massive piece of glacier sheared away from the mountain along a section of constantly shifting ice and crevasses known as the Khumbu Icefall — a treacherous area where overhanging ice can be the size of office buildings.

The disaster has reignited a debate over the disproportionate risks the Sherpas take on Everest, where most climbers are well-heeled amateurs with little or no experience at high altitudes. That means Sherpas are needed to create miles of lines of fixed ropes, carve steps in the ice and snow and carry nearly all the equipment. At times, they are also "short-roped" directly to weak climbers to help them get up the mountain.

Mount Everest Sherpas

Relatives carry the body of Ankaji Sherpa, who lost his life in an avalanche at Mount Everest last Friday, during the cremation ceremony of Nepali Sherpa climbers in Kathmandu on Monday. (Navesh Chitrakar/Reuters)

Because of their additional work, many have to pass through the Khumbu Icefall dozens of times, each time exposing themselves to the treacherous conditions there.

Immediately after the avalanche, the government said it would pay the families of each Sherpa who died 40,000 rupees, or about $415. But the Sherpas said they deserved far more — including more insurance money, more financial aid for the victims' families and new regulations to ensure climbers' rights.

Nepal's government appeared to agree Tuesday to some of the demands, such as setting up a relief fund for Sherpas who are killed or injured in climbing accidents, but the funding fell far short of the demands.

New government support

The government's offers include a relief fund to help Sherpas injured in mountaineering accidents and the families of those killed, and to pay for rescue during accidents on the mountain. The government said it would stock the fund annually with 5 per cent of its earnings from Everest climbing fees — well below the 30 percent the Sherpas are demanding. Nepal earns about $3.5 million annually in Everest climbing fees.

The insurance payout for those killed in the avalanche, which now stands at $10,400, will also be increased to $15,620, or 2 million rupees, the Ministry of Tourism said — far less than the Sherpas' demand for $20,800.

The Nepal National Mountain Guide Association will also try to negotiate with the Sherpas and the government because a total boycott would harm Nepal's mountaineering industry in the long term, said the group's general secretary, Sherpa Pasang.

Nearly 30 climbers have died on the Icefall since 1963, most killed in avalanches or when they were crushed by huge chunks of ice.

More than 4,000 climbers have reached the top of the world's highest mountain since 1953, when it was first conquered by New Zealander Edmund Hillary and Sherpa Tenzing Norgay. Hundreds of people have died trying.

With files from CBC News