A British man and his Nepali guide are believed to be dead after reaching the summit of Mount Everest on Tuesday, a guiding company said. Dan Paterson, 40, and Pastenji Sherpa, 23, reached the peak just before 5am on Tuesday but have not been heard from since, according to Paterson’s partner, Becks Woodhead. Paterson’s partner has set up an online crowdfunding page for the search and rescue operation and said that a helicopter and specialised search teams are likely to cost about £150,000. The GoFundMe site had reached £118,000 on Saturday evening. “Dan’s family and I urgently need your help,” Woodhead posted on the site. “Tragically, during his descent, Daniel went missing, and there has been no contact or sighting of him since. “Time is of the essence in a situation like this, and we are mobilising every resource we can to locate Dan. “Conducting a search and rescue operation on Everest is an incredibly complex and costly endeavour. We are not experts in this, and there is no guarantee of success.” Lakpa Sherpa, the founder of guiding company 8K Expeditions, which both men used, said they searched for the pair after they “heroically” reached the peak of Everest at 4.40am (11.55pm in the UK). Sherpa added: “Despite exhaustive search efforts, we regret to confirm that Daniel and Pastenji were unable to be recovered.” The news that the rescue was being called off came amid reports of more deaths. The Kenyan Joshua Cheruiyot Kirui, 40, was found just 19 metres below the summit, having gone missing on Wednesday. The 44-year-old guide who was with him, Nawang Sherpa, is still missing. A Nepali climber, Binod Babu Bastakoti, died of an illness while descending on Thursday. Footage posted on social media showed crowds of mountaineers queueing to climb the summit this week, which experts say puts the climbers at an increased risk. Tuesday was the busiest day of the Everest season, with an estimated 200 mountaineers taking advantage of a weather window to attempt climbing to the summit, according to Nga Tenji Sherpa. Videos and photographs online appear to show hundreds of people on the Hillary Step, an almost vertical rock face near the top of Everest at about 8,800m. Paterson’s disappearance comes after a landslide of snow and ice on the mountain. A cornice – a mass of hardened snow overhanging the edge of a precipice – is thought to have collapsed, dragging climbers down the side of the mountain. Alan Hinkes, a mountaineer who reached Everest’s summit in 1996, told Sky News: “You can only survive for a few hours at that altitude. It’s the death zone, because of the lack of oxygen, air pressure, and really cold temperatures. “So hanging around in one of those queues isn’t a good idea, because you’re slowly dying in those altitudes.” Vinayak Malla, an International Federation of Mountain Guides Associations guide who climbed Everest earlier this week, wrote on Instagram that reaching the summit “felt different than my previous experiences”. He added: “After summiting, we crossed the Hillary Step, traffic was moving slowly then suddenly a cornice collapsed a few metres ahead of us. There was also a cornice under us. “As the cornice collapsed, four climbers nearly perished yet were clipped on to the rope and self-rescued. “Sadly, two climbers are still missing. We tried to traverse yet it was impossible due to the traffic on the fixed line.”