A Nepali rescue team searching for four missing South Korean trekkers in the Himalayas has dispatched rescue dogs and drones to assist in operations which are now entering their sixth day.

After resuming their search early Thursday, the team of military officers and civilians deployed two dogs who had previously played a key role in rescuing survivors after an avalanche.

A drone search team led by renowned South Korean mountaineer Um Hong-gil carried out a separate search and plans to use more advanced heat-seeking drones aside from the previous two in operation.

Additional avalanches and rains have repeatedly hampered search efforts since last Saturday.

Four teachers from South Korea's central South Chungcheong Province were trekking with five others on the Deurali part of the Annapurna Base Camp course last Friday when an avalanche struck them and three Nepali guides.