"Japan decides on the area (of evacuation around the plant) based on experts' advice and proposals," Kan said. "In Japan, we ask people to follow the rules because if they do, there will be no damage to their health."

Japan has resisted a nudge from the UN nuclear watchdog this week to widen the 20-kilometre evacuation zone around the nuclear plant and clear people out of the village of Iitate, 40 kilometres (25 miles) northwest of the facility.

The government has also halted shipments of farm and dairy produce from four prefectures near the plant, while authorities in and around Tokyo last week urged parents not to use drinking water in baby formula after elevated iodine levels were found.

"The government has summoned the capabilities of all experts possible to stabilise the plant. But the situation has not yet reached the point where we see it as stabilised," Kan said.