Japan has declared a 20km area evacuated around the crippled Fukushima Daiichi nuclear power plant a no-go zone.

Yukio Edano, the country's chief cabinet secretary, said on Thursday that the order would take effect from midnight local time on Friday (1500GMT on Thursday), and was aimed at preventing unrestricted entry into an area that has been largely deserted since an evacuation order first went out following the March 11 earthquake and tsunami.

Under Japan's Disaster Countermeasures Basic Law, anyone who enters the zone will be subject to fines of up to 100,000 yen ($1,200) and possible arrest. Before the measure was enacted, defiance of the government's evacaution was not punishable by law.

"We beg the understanding of residents. We really want residents not to enter the areas," Edano said. "Unfortunately, there are still some people in the areas."

Edano termed the plant's condition as "not stable".

"[The declaration] reflects a growing worry from the Japanese government that people have been getting into this area much too easily and without enough caution," reported Harry Fawcett, Al Jazeera's correspondent in Sendai.

"The evacuation zone has been off-limits in terms of people living in their homes ... but police around the checkpoints bordering it haven't been able to ... prevent people from coming in. All they've been able to do is take licence plate numbers and instruct people to get a radiation check when they come out."

Families still in zone

Almost all of the around 80,000 residents of the area had left when evacuation was ordered on March 12, but police say that more than 60 families are still living inside the affected zone. Our correspondent said many had returned to retrieve possessions or money from their homes.

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Edano said residents would be allowed to conduct brief visits to collect their belongings, with the authorities allowing one person per household to return by bus for a maximum of two hours. The residents would be required to go through radiation screening, he said, though the details of the plan are still being worked out.

"We realise this is extremely inconvenient for residents, but we urge you to be patient," Edano told reporters in Tokyo.

Officials said that the no-go zone was meant mainly to limit people's exposure to radiation and to control entry in order to prevent thefts. The government had earlier declared a 30km evacuation zone, and suggested that residents of areas further afield may also soon be told to leave due to the risk of long-term radiation exposure.

Government under fire

On Thursday, Naoto Kan, Japan's prime minister, visited the region to meet with local officials and evacuees in order to discuss the setting up of the evacuation zone and the enforcement of its boundaries.

The prime minister, who has come under fire for the government's response to the crisis, was also to meet with officials at a nuclear crisis management centre.

On Wednesday, however, Edano had suggested that Tokyo Electric Power Company (TEPCO), the operator of the stricken nuclear plant, should have been better prepared.

"Aside from the question of whether the accident could have been predicted, there was not sufficient preparation based on an anticipation, and there is no mistake about that," he said. "We urge all nuclear operators to immediately take any possible precaution based on the lesson from the Fukushima nuclear accident, and not wait until details of the accident are examined."

Kan met with Julia Gillard, the Australian prime minister, later on Thursday.

Gillard said that the two countries' foreign and defence ministers will be meeting in the coming weeks to discuss collaboration on disaster management efforts. She also assured the Japanese PM that Australia was a reliable energy supplier to the country, and it will continue to be so.

More older people died

At the Fukushima plant, TEPCO began on Wednesday to pump out 25,000 metric tons of highly radioactive water from the basement of one of the turbine buildings. The process will take at least 20 days, nuclear safety officials say. In total, 70,000 tons of contaminated water will need to be disposed of from the plant and the trenches around it in a process that could take months.

Those conducting the dangerous repairs on the plant continue to face health concerns, Al Jazeera's Fawcett reported.

"A doctor who visited the workers doing this very dangerous work says that their own health is now suffering, if not from radiation then certainly from the psychological stress they've been undergoing. Insomnia and heart conditions, he was talking about," he said.

More than 13,000 people were killed and tens of thousands lost their homes when the 9.0 earthquake and 15-metre tsunami hit Japan's northeastern coast last month.

New data from the country's National Police Agency shows that 65 per cent of those confirmed to have died in the disaster were aged 60 or older. The agency said that nearly 93 per cent of fatalities in the aftermath of the disaster were caused by drowning.

More than 130,000 people were in shelters at the start of this week, police figures showed.

Source: Al Jazeera and agencies