Two foreign mountaineers have returned to Everest after a deadly avalanche effectively ended the climbing season, flying by helicopter partway up the peak before starting their ascent, an official said Tuesday. The climbers, from the United States and China, took the rare step of hiring a helicopter that flew them above the Khumbu Icefall, where the worst accident in the mountain's history last month killed 16 sherpa guides, the air charter company said. The climbers, thought to be the first back on the mountain since expeditions left following the April 18 disaster, flew from Everest base camp to Camp 2, skipping the section where the avalanche hit. "Two climbers are heading up from Camp 2," tourism ministry official Dipendra Poudel told AFP. "There are also other climbers who have shown interest to continue their expeditions this year." The Chinese climber, accompanied by six sherpas, is attempting to scale Everest while the US mountaineer is heading alone for neighbouring Lhotse peak. Lhotse and Everest share the same route as far as Camp 3. "This is the first time we've taken climbers up to Camp 2. Earlier we made such flights to transport only equipment or in cases of emergencies," said Ramesh Shiwakoti from Fishtail Air, which flew the climbers. Shiwakoti said they had decided to fly to Camp 2 because the route below, normally set up by sherpas beforehand with ropes and ladders, has not been completed this season. Most climbers abandoned plans to ascend Everest from the Nepalese side -- the easiest and most popular route up the world's highest peak -- after the avalanche. The disaster sparked a labour dispute between the 600-strong sherpa guides and the government, and a boycott by most sherpas that left foreign expeditions no choice but to abandon plans for the season. But the government did not officially declare a halt to this year's season, a key revenue earner for the impoverished country, and has encouraged climbers to continue their expeditions. The disaster highlighted the risks taken by guides on behalf of foreign clients and fuelled demands for better death and injury benefits after the government initially offered $400 to families of those killed. The window for climbing Everest lasts until May 25, after which the temperature gets warmer and the mountain more dangerous.