Plutonium believed to have come from a stricken nuclear plant in north-east Japan has been found in a town near the facility, but researchers are downplaying its significance.
The Fukushima Daiichi plant was badly damaged after a 9.0 magnitude earthquake triggered a tsunami on 11 March.
For the first time since the disaster, plutonium has been found in the town of Okuma 1.7km from the plant, the ABC reports.
Researchers say the amount detected is lower than the average level usually observed in Japan after fallout from nuclear tests abroad.
Earlier, Japan's nuclear agency revealed it had doubled its estimate of the radiation released by the Fukushima plant in the aftermath of the disaster.