KATHMANDU: The rescue operation to search for missing South Korean climbers and accompanying Nepali guides have been called off after four days of intensive search. Four South Korean climbers and three Nepali guides have been missing after avalanche hit a trekking route in the Annapurna region last week. As landing was difficult, search for the seven missing persons were carried out from a helicopter on January 19, informed Ngawa Ngima Sherpa of Korea Tours and Trekking Operators Association Nepal. A more extensive ground search began from January 20 to January 23 but not without difficulties due to bad weather and other smaller avalanches, Sherpa added. The search was carried out with the best available technology including metal detectors, recco detectors, drone cameras, among other equipment, stated Sherpa. 'The operation was assisted by Machhapuchchhre Rescue Centre, jointly established by Korea Telecom and Nepal Mountaineering Association (NMA).' International guides and Simrik Heli rescue team also provided their support to find those missing in the deep snow, Sherpa, who was coordinating with the rescue team from Pokhara, said. Trained rescue dogs were mobilised in the effort to not miss any chance of finding them. The search operation was led by legendary Korean climber Captain Um Hong Gil, Sherpa said. Boosting the search effort was a team of nine Nepal Army personnel from Pokhara along with local hotel entrepreneurs. However, due to continued avalanches and bad weather condition, the search had to be called off for now, informed Sherpa. 'On Korean Embassy's request, Government of Nepal could take further initiative to continue the search mission, with the help of locals, when the weather changes and snow melts.' The trekkers went missing from Deurali area in Kaski district after the avalanche triggered by heavy snowfall hit the trail route on January 17.