TOKYO — Japan declared a 12-mile (20-kilometer) area evacuated around its radiation-spewing nuclear power plant a no-go zone on Thursday, urging residents to abide by the order for their own safety or possibly face fines or detention.

The order, due to take effect at midnight, angered residents who fled their homes nearly empty-handed when they were told to evacuate after last month's tsunami and earthquake wrecked the Fukushima Dai-ichi plant's power and cooling systems.

"I initially thought we would be able to return within a few days. So I brought nothing except a bank card," said Kazuko Suzuki, 49, from Futaba, just next-door to the nuclear complex.

"I really want to go back. I want to check if our house is still there," said Suzuki, who fled with her teenage son and daughter. "My patience has run out. I just want to go home."

Officials said the order was meant to limit exposure to radiation leaking from the plant and to prevent theft in the mostly deserted area.

Under a special nuclear emergency law, people who enter the zone will now be subject to fines of up to 100,000 yen ($1,200) and possible detention of up to 30 days. Up to now, defiance of the evacuation order was not punishable by law.

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

The new ruling was not due to any particular change in conditions inside the plant, which appear to have somewhat stabilized. Even under the best-case scenario, however, the plant's operator says it will take at least six months to bring its reactors safely into a cold shutdown.

Almost all the zone's nearly 80,000 residents left when the area was evacuated on March 12, but police had not been able to legally block them from going back. Police contacted Thursday said they had no estimate of the exact number of people who have returned to the zone or who still might be living there.

Edano said authorities would arrange brief visits for residents, allowing one person per household to return by bus for a maximum of two hours to collect necessary belongings. Residents would be required to go through radiation screening, he said.

Residents chafed at the limit to just one person per household.

"It's outrageous. I can do very little within two hours. The government does not understand our needs and concerns," Suzuki said.

No visits will be allowed in a two mile (three kilometer) area closest to the plant, said Hidehiko Nishiyama of Japan's Nuclear and Industrial Safety Agency, confirming reports that zone would be completely off-limits.

Details were still being worked out.

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

Prime Minister Naoto Kan was visiting the region Thursday to meet with local officials and evacuees to discuss the plans for strict enforcement of the evacuation zone.

Kan also visited a nuclear crisis management center in Fukushima, giving a pep talk to workers there. He has been under fire from the opposition for the government's response to the nuclear crisis.

Fukushima's governor, who has also expressed frustration with the crisis, said he strongly urged Kan to ensure the government properly handles the disaster and related compensation issues.

"I told the prime minister that I strongly hope that evacuees can return home as early as possible," said the governor, Yuhei Sato.

Meanwhile, new data from Japan's National Police Agency showed that two-thirds of the victims identified so far in last month's earthquake and tsunami were elderly — and almost all of them drowned.

The agency said 65 percent of the 11,108 confirmed fatalities of known age were 60 or older. Another 1,899 victims were of unknown age.

With another 14,000 people still missing, the March 11 disaster is believed to have killed about 27,000. The police agency said nearly 93 percent of the victims had drowned. Others perished in fires, were crushed to death or died from other causes.

The northeastern coast hardest hit by the disasters had a high concentration of elderly residents. (AP)