January 19.(AP)

An operation to rescue at least six people missing after an avalanche in north-western Nepal has been delayed by poor weather, officials say.The trekkers were on route on a Himalayan mountain near a base camp in the Annapurna region when the avalanche struck after heavy snowfall on Friday.

Four South Koreans – all volunteer teachers – and at least two Nepali guides are among those missing.A number of other trekkers were rescued from the site of the avalanche.Heavy snowfall – as much as 5m (16ft) at the scene of the avalanche – delayed rescue efforts on Saturday, South Korea’s Yonhap News Agency reported.But the rescue mission was set to resume on Sunday, with helicopters and 10 more police officers expected to join the search on Mount Annapurna, one of the highest peaks in the Himalayas.The avalanche happened at an altitude of 3,230m (10,600ft) about 150km (93 miles) north-west of Nepali capital Kathmandu, officials say.