An Australian woman and her three sons have been rescued after spending a freezing night on a mountain in Japan.

The four were reported missing late on Monday after failing to return to the popular Nozawa Onsen ski resort on Mount Kenashi.

They were rescued about 08:40 local time on Tuesday, Japanese media said.

It is understood the woman, aged in her 50s, her two adult sons and a younger son dug themselves into a snow hole for shelter.

None appeared to be seriously injured, local media quoted police as saying.

Long ordeal

"The four were shaking considerably when found," a rescuer told broadcaster NHK.

"But after providing them with food and hot water, they stopped shaking. They barely survived as they spent the night without much on them. Not moving around must have helped a great deal."

Authorities began searching for the family after they managed to post a message on Facebook calling for help, TV Asahi reported.

Police said the four were unable to descend from the 1,649m mountain, 200km (125 miles) north-west of Tokyo, after a day of skiing.

Temperatures dropped as low as -10C during the night, following three days of heavy snowfall, the Australian Broadcasting Corporation said.

Australia's Department of Foreign Affairs and Trade confirmed it had been in contact with officials in Japan.