Police and fire officials in one of Japan's most famous ski resort areas have resumed a search operation on Monday.

They are looking for at least two people who were caught in an avalanche. They were among a number of foreigners that were skiing out of bounds.

Police say the avalanche struck in the backcountry near the Tsugaike Mountain Resort in Nagano Prefecture on Sunday afternoon.

At least three groups of foreign skiers were there at the time.

Rescue crews gathered and headed up to the site early on Monday morning.

They are searching for two people who were reported to be unconscious after the slide.

And crews are searching for another missing man in the mountains of Nagano.

The 38-year-old man is believed to have been snowboarding out of bounds near the Nozawa Onsen Ski Resort. He has been missing since Saturday.