This combination of two photos, taken over a six-month period, shows the aftermath of the March tsunami and its cleanup progress in Iwaki, Fukushima Prefecture, in northeastern Japan. The top photo was taken on March 11 while the bottom photo was taken Sept. 1. (Kyodo News)

Japan lifted some evacuation advisories around the tsunami-devastated Fukushima Daiichi nuclear plant Friday to reassure tens of thousands of residents, who fled the worst atomic crisis since Chornobyl, that it is safe to return home.

A 20-kilometre no-go zone remains in place around the nuclear plant, which was badly damaged by the March 11 tsunami that left nearly 20,000 people dead or missing across Japan's northeast coast.

But officials said the advisories for five municipalities that are 20 to 30 kilometres away were lifted because the plant had been restored to a relatively stable condition and radiation levels were within safety standards.

Major step toward restoring normalcy: crisis official

Environment Minister Goshi Hosono, the government's top nuclear crisis official, said the decision was a major step toward restoring normalcy to the region and boosting efforts to resettle the largely deserted towns.

Local officials, however, said they did not expect residents to come flooding back right away.

'We are doing all we can to assure that our townspeople will be able to return as soon as possible.' —Motohoshi Yamada, mayor of Hirono

Motohoshi Yamada, the mayor of one of the affected towns, said in a statement Friday that further radiation monitoring and infrastructure repairs must be carried out before the town will be ready to function again.

"We are doing all we can to assure that our townspeople will be able to return as soon as possible," said Yamada, whose town, Hirono, is right on the edge of the no-go zone. "As soon as we believe residents can return safely and securely, we will let them know."

The advisories were issued April 22 and affected about 59,000 people.

Tens of thousands remain in voluntary exile

The government did not order residents outside the 20-kilometre zone to leave. Instead, it cautioned them to be prepared to remain indoors or evacuate at any time in the event of a further crisis at the plant. Many — fearing radioactive contamination and cut off from public services — left anyway.

The five towns have begun efforts to decontaminate buildings and restart public services so that residents can return. A government panel is also compiling guidelines to address concerns from residents and support their resettlement process.

Experts say it could take decades for some of the areas nearest the plant to be safe for habitation.

The disaster is the worst since Chornobyl in 1986.

Still, the plant's operator, Tokyo Electric Power Co., announced this week that it was making significant progress toward controlling the temperatures in the reactors, a key to stabilizing them and eventually shutting them down altogether.