Tokyo (CNN) -- Radiation levels in a Japanese town outside a government-ordered evacuation zone have exceeded one of the criteria for evacuation, the International Atomic Energy Agency said Wednesday.
The agency said it advised Japan "to carefully assess the situation."
The elevated levels were found in Iitate, a town of 7,000 residents about 40 kilometers (25 miles) northwest of the earthquake- and tsunami-damaged Fukushima Daiichi nuclear power plant, the agency said. The evacuation zone covers a 20-kilometer (13-mile) radius around the plant.
The agency did not say what levels it found in Iitate, but the environmental group Greenpeace said Sunday it had found radiation levels in the town that were more than 50 times above normal.
Though that is far below the level that would cause radiation sickness, it does pose a risk of cancer to residents in the long term, Greenpeace said.
Three types of plutonium have turned up amid the radioactive contamination on the grounds of the earthquake-damaged Fukushima Daiichi nuclear power plant, its owner reported Monday.
The plutonium is a byproduct of nuclear reactions that is also part of the fuel mix at the damaged No. 3 reactor.
It was found in soil at five different points inside the plant grounds, the Tokyo Electric Power Company said late Monday.
Plutonium can be a serious health hazard if inhaled or ingested, but external exposure poses little health risk, according to the U.S. Environmental Protection Agency.