TOKYO - Japan has ordered authorities to be ready for a widening of the exclusion zone around a crippled nuclear plant as worries mount over the effects of long-term radiation exposure, officials said on Monday. People living within a 20-kilometre (12-mile) radius of the Fukushima Daiichi power plant have already been ordered to leave, while those living up to 10 kilometres beyond that have been told to stay indoors.
"We have been told by the government that an evacuation order will likely be given to some districts of the town," said Yoshiyuki Takahashi, an official from Kawamata town, which lies entirely outside of the plant's 30-kilometre zone.
"But we don't know when it will be. One month or three months, we don't know," he said.
Environmental pressure group Greenpeace on Monday called for high-risk people in Fukushima city, 80 kilometres away to be evacuated, saying children and pregnant women were particularly vulnerable.
The organisation also called on the Japanese government to fully evacuate what it called "radiation hotspots", including the towns of Iitate and Namie, after finding "widespread caesium contamination".
"People in the greater Fukushima area could potentially receive radiation exposure of more than five millisieverts per year," said Greenpeace's Rianne Teule.
Greenpeace said its monitoring teams recorded radiation levels of four microsieverts per hour in a playground in Fukushima city, a level it said was high enough to expose people to the maximum yearly dose of radiation in a few weeks.
Before Greenpeace published its findings, Chief Cabinet Secretary Yukio Edano told reporters any increase in the evacuation zone would unlikely be a uniform one.
"It will not be a clear circle. We are taking into account detailed analysis based on data from monitoring and considering contours and geography in the area," he said.
"The government has begun consulting with municipalities concerned based on the results."
Japan's evacuation order is currently issued based on the IAEA standard, under which residents are ordered to leave for at least seven days when the initial exposure level to radiation hits 50 millisieverts.
"The government is now considering reviewing the evacuation standard that should apply to a nuclear accident that continues for a longer period," said an official of the Nuclear Safety Commission.
Under the International Commission on Radiological Protection, exposure levels between cumulative 20-100 millisieverts per year are applied for an evacuation in emergency.
Data have shown higher levels of contamination in some areas outside the current evacuation circle, raising concerns for accumulated exposure risks in municipalities including Kawamata and Iitate village.
Iitate mayor Norio Kanno said he was frustrated by the situation.
"There are places showing high levels and low levels (of radiation) in the village," he told NHK.
"I argued there should be many ways to keep total exposure levels low (while still staying in the village), but unfortunately my request was not accepted," he said.