In one of the worst tragedies on Mount Everest in Nepal, at least 12 Sherpa guides and mountaineering support persons were killed after an avalanche swept down a climbing route on Friday, a Nepali government official said.

Four other Sherpas who were injured have been taken to hospital. The rescue operation was affected due to bad weather in the Lukla region. It would resume on Saturday.

There were conflicting reports of the exact number of those swept away by the avalanche. An official at the Ministry of Culture, Tourism and Civil Aviation said 25 Sherpas were trapped. Eight of them have been rescued. The bodies were buried under mounds of snow.