Japanese authorities Tuesday said they had found all the people left missing after massive floods that devastated large areas north of Tokyo, killing seven and destroying thousands of homes.

Fourteen of the 15 people who were unaccounted for were confirmed found by Tuesday morning after rescuers went door-to-door to damaged houses.

The last missing person was discovered safe at a shelter, said Mitsuharu Omine, a local government official.

The slow operation to confirm the whereabouts of the missing people was partially due to damage to infrastructure, including telephone lines, he added.

Parts of Joso, a community of 65,000 residents, were washed away last week when a levee on the Kinugawa river gave way, flooding an area spanning some 40 square kilometres (16 square miles) after the worst rains in decades.

Thousands of rescuers -- troops, police and firefighters -- were deployed to search for the missing and to help hundreds of others trapped by the waters in eastern Japan.

"Now no one is now on the missing list," Omine told AFP, but added: "We will continue our search as more victims could be found."

Seven people died in the floods and more than 12,000 homes and buildings were submerged.

Officials said more than 2,600 people were still at evacuation centres mainly in Joso as the water supply to the city remained cut off.

Torrential rain also lashed areas in the region surrounding the crippled Fukushima nuclear plant, washing away hundreds of bags of soil and grass that may been contaminated when it melted down four years ago.

The environment ministry said 81 bags were missing and 163 bags were found broken, although they were not believed to be dangerous, adding: "It would take time to check the impact of the case on the environment."