The man, in his 20s, was in shock and unable to speak when he was found in Kesennuma in Miyagi prefecture, one of the regions hardest hit by the magnitude 9.0 earthquake, a spokesman said.

He was found trapped on the second floor of a house and had wrapped himself in a blanket, Kyodo news agency said. He was conscious and his blood pressure and pulse were stable.

He was found a day after authorities said they had ended the rescue phase of the post-earthquake operation and would be concentrating on clearing rubble and restoring limited services.

It was not immediately clear how the man survived in an area where overnight temperatures have plunged below freezing.

Nearly 7,000 people have been confirmed killed in the double natural disaster, which turned whole towns into waterlogged and debris-shrouded wastelands.

Another 10,700 people are missing with many feared dead.

(Reporting by Kazunori Takada; Editing by Nick Macfie)