The whole of Futaba, formerly home to some 7,000 people, was designated a mandatory evacuation zone after a massive quake-triggered tsunami in 2011 hit the Fukushima Daiichi plant, damaging the power supply and cooling system and eventually causing a meltdown.

With the lifting of the mandatory evacuation order in a northern part of the town, workers will be able to stay in the area near the main railway station.

But residents will not be able to return to the town immediately because of a shortage of running water and other infrastructure, a town official told AFP.

"We are aiming to have the return of residents starting in the spring of 2022," she said.

The move comes after organisers of the Tokyo 2020 Olympics said Futaba has been added to the route for the Olympic torch relay, which begins on March 26.

"In addition to building excitement across the country ahead of the Tokyo 2020 Games and promoting the Olympic values, the Olympic Torch Relay aims to demonstrate solidarity with the regions still recovering from the 2011 earthquake and tsunami," the organisers said last month.

The Japanese government is keen to use the Olympics to showcase Fukushima's recovery from the disaster.

It intends to use the J-Village -- a sport complex located about 20 kilometres (12 miles) from the nuclear plant damaged in the 2011 tsunami -- as the starting point for the Japan leg of the torch relay.

The Fukushima crisis itself did not directly kill anyone, but some 470,000 people were estimated to have fled their home to seek shelter in the first days of the triple earthquake-tsunami-meltdown disaster.

In all, 15,899 people died and 2,529 people remain missing after the quake and tsunami.