Thousands of parents living near Japan’s stricken Fukushima Daiichi power plant have condemned a government decision to lift radiation limits for schools in the area by 20 times, saying the move is based on incomplete science and could put children in danger.

The decision, which has also prompted the resignation of a government adviser, has been condemned as political expediency. Toshiso Kosako, the adviser who resigned on Friday, denounced the Prime Minister, Naoto Kan, for his “whack-a-mole” policies on the crisis. A tearful Mr Kosako said: “The government has belittled laws and taken decisions only for the present moment.”

He said new guidelines raising the acceptable annual radiation exposure in Fukushima Prefecture’s elementary schools from one to 20 millisieverts “are inconsistent with internationally commonsensical figures” and were “determined by the administration to serve its interests”.

But it is the voices of local parents that are likely to prove hardest for the government to ignore. Takayuki Sasaki, a baker and father of two, barely knew what radiation was two months ago. Today, he thinks about little else. “I’ve sent my kids to my wife’s family in Tokyo,” he says. “I told her to stay there till it’s safe but who knows when that will be? We’ve all been left in the dark.

“Those parents who have the means to move their children are already doing so,” Mr Sasaki adds. “I feel like one of the lucky ones because my wife is from Tokyo.”

In the seven weeks since the crisis began more than 80,000 people have been evacuated from a 20km zone around the Fukushima plant. The power station has been leaking radiation since the earthquake and tsunami triggered a partial meltdown of its reactors.

Mr Kan’s government has repeatedly defended the new limits, which are equal to the annual maximum dose permitted for German nuclear workers. Workers at power plants in the United States can be exposed to 50 millisieverts per year. The average annual radiation exposure from natural sources is about 3.1 millisieverts.

The impact of cumulative exposure on children, however, is a scientific grey area. Parents in Fukushima say the government’s calculations are deceptive because they assume people spend most of their time indoors.

“I keep my children inside now all the time because I’m afraid of what they’re breathing,” said Niki Soeta, a mother of two from the prefecture. “Can the government imagine what that’s like? We want to be reassured that it’s safe.” She was among hundreds of parents who gathered yesterday in a meeting hall in Fukushima City to plan strategy and protests against the government policy.

“We’re all absolutely furious,” said Machiko Sato, banging the table for emphasis. “We’re angry at the government and at Tepco [Tokyo Electric Power] for doing this to us. We’re breathing in this contaminated air as we speak. But we’re old and the radiation can’t do us much harm. It’s the children we have to protect.”

Parents and lobbyists are scheduled to meet bureaucrats today to hand over a petition demanding the withdrawal of the new radiation standard. Activists say the country’s Nuclear Safety Commission rubber-stamped the school radiation limit after just two hours of closed-doors discussion, without consulting anyone outside the government.

Mr Kosako also criticised the government for stalling the release of simulations showing the spread of radiation from the Fukushima plant. The head of Japan’s Meteorological Society, Hiroshi Niino, admitted last week that announcing all the radiation forecasts carried the risk of “creating panic” among the public.

Mr Sasaki said: “The system isn’t working because it’s top down. The officials from the Nuclear Safety Commission tell the government what they’ve decided. The government tells Fukushima. Fukushima tells the schools and the school principals tell us that it’s safe. That’s when I knew it was time to get my kids out of school. I just don’t believe them.”