The number of dead from Japan's heaviest snowfall on record has risen to nearly 70 people.

The 68th death linked to the snow occurred on Sunday night, when a 57-year-old man fell into an irrigation ditch in Yamagata prefecture.

Earlier the same day, another man who had been missing since Dec. 30 was found under a two-metre-high pile of snow beside his home in the city of Hirakawa.

More than 1,000 others have been injured in accidents related to the snowfall, which began in early December.

It has piled up more than three metres deep in some of the worst-hit areas of Niigata prefecture, northwest of Tokyo.

The Japanese government has deployed teams of soldiers to help clear the snow in Niigata prefecture, one of the country's 47 administrative districts.

Troops are also trying to re-open roads blocked by snow in Nagano prefecture, which is also northwest of the capital.

The government of Akita prefecture on Sunday asked for troops to help out in its region, which has seen the heaviest snowfall in more than 30 years.

Some of the victims were killed as roofs collapsed under the weight of the snow.

Others died in falls while trying to remove the snow from their roofs.

The Japanese Meteorological Agency was predicting more snow in northern and western parts of the country.

The snowfalls are part of of a wider swathe of cold weather that has afflicted several parts of Asia recently.

Among them, India has reported more than 130 deaths linked to the cold wave and others have died in Bangladesh.

In China, thousands of people have been forced to flee their homes after roofs collapsed under heavy snow and some cattle have reportedly frozen to death.