Twenty-six people remained in hospital, with seven of them suffering serious injuries, police said. Nine people were killed, all of them construction workers who were meeting in a makeshift two-storey office building.

Television footage Wednesday showed small homes and buildings torn to pieces and cars overturned as the twister ripped through the town.

"I was working at my desk when the incident occurred. It took me about 20 minutes to crawl out of the debris," said Masaru Mito, whose office at a timber company collapsed completely.

Some 20 government officials headed by federal disaster chief Kensei Mizote were visiting the site to see the extent of damage and the conditions of survivors, an internal affairs ministry official said.

They were accompanied by meteorological experts and would later be joined by Land, Infrastructure and Transport Minister Tetsuzo Fuyushiba.

"Our staff members began this morning to investigate details of the damage at the site and to collect scientific data," said Satoru Iino, a spokesman for the Japan Meteorological Agency.

Fifty-six people whose homes were damaged spent the night at a public gymnasium, a police spokesman said.

"Today we will continue investigating the details of damage, together with the fire department and possibly the self-defense forces," he said, referring to the officially pacifist country's military.

Tornados -- known in Japanese as "tatsumaki" or "spiralling dragons" -- are relatively rare in the island nation, which is routinely hit by typhoons and earthquakes.

Saroma, a town of 6,200 people whose main industries are dairy farming and scallop fishing, is known to Japanese mostly for the nearby top-security Abashiri prison which holds some of the country's top gangsters.

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