KATHMANDU : Three major mountaineering companies joined others in quitting Everest citing fears of violence, safety concerns and tension at base camp, deepening a crisis Thursday on the world’s highest peak sparked by the death of 16 guides last week.

International expeditions said they were shutting down operations on the mountain, as a Nepalese government delegation was set to fly to Everest base camp to try to cool tensions and save this year’s climbing season.

Sherpas distraught over the death of their colleagues and demanding more compensation and other benefits have threatened to boycott the season after the avalanche on Friday, the worst ever on the world’s highest peak.

Leading US mountaineering company International Mountain Guides said the main route through the Khumbu Icefall, where the avalanche struck a team of guides carrying equipment for their clients, was too dangerous.

“The icefall route is currently unsafe for climbing without repairs by the icefall doctors (highly-skilled guides who fix ropes and repair ladders up the mountain), who will not be able to resume their work this season,” IMG said in a statement.

Announcing it was also cancelling its expedition, US company RMI Expeditions said “the risks outweigh the possibility of success”.

Peak Freaks, led by Canadian mountaineer Tim Rippel, said “the route in my professional opinion is NOT safe” saying there was a real threat of further avalanches.

“In addition 300+ sherpas have put their names on an organized protest to not climb in respect of the recent deaths, why wouldn’t we listen to them?” Rippel said in a post online.

Describing a tense environment at base camp, he said sherpas keen to close down the climbing season were threatening violence against those who wanted to continue. Mountaineering companies and officials were also pressuring guides to stay on the mountain, he said.

“It’s gotten too messy...now that we have an army, police and angry sherpas staging at base camp, it’s time to go home,” Rippel wrote.

Three other expeditions have already cancelled their plans to scale the 8,848-metre (29,029-foot) peak, and the latest announcements throw the climbing season into further disarray.

Under fire over its handling of the disaster, the Nepal government is desperate to avoid a shutdown of the season that could lead to messy refund claims and a huge loss of revenue for the impoverished country.

A team of government officials was expected to arrive at base camp Thursday and attempt to work out a deal with the sherpas.

Sherpas on Tuesday threatened to abandon the season, after issuing a string of demands to the government, including higher compensation for the dead and injured, an increase in insurance payments and a welfare fund.

The avalanche underlined the huge risks borne by sherpas who carve out the routes and carry gear up the mountain for their foreign clients. The tragedy also reignited debate about whether the government does enough for sherpas who are key to the industry’s success.

The government has offered to set up a relief fund for injured guides using up to five percent of fees paid by climbers, while increasing life insurance payments by 50 percent, both amounts falling short of the sherpas’ demands.

The government, which has earned $3.6 million this year from Everest climbing fees alone, has issued permits to 734 people, including 400 guides, for 32 expeditions this season.