The Japanese government says it has detected plutonium outside the crippled Fukushima nuclear plant for the first time.
The plant was badly damaged by the massive earthquake and tsunami that hit Japan in March.
Japan's science ministry says small traces of plutonium were detected in samples taken from six communities ranging from a few kilometres to up to 45km from the Fukushima plant.
The ABC reports that all locations are north-west of the facility and the plutonium is believed to have been blown there after the disaster.
An expert has told Japan's NHK network that if ingested or inhaled plutonium can remain in the body for a long time and cause cancer.
One of the types found, plutonium 239, has a half-life of more than 24,000 years.
Immensity of nuclear clean-up revealed
Japan's environment ministry says it faces the prospect of removing and disposing of 29 million cubic metres of soil contaminated by the world's worst nuclear crisis in 25 years from an area nearly the size of Tokyo.
Six months after the 11 March earthquake and tsunami triggered reactor meltdowns, explosions and radiation leaks at the Fukushima nuclear power plant, the size of the task of cleaning up is only now becoming clear.
The ministry says contaminated zones where radiation levels need to be brought down could top 2,400 square kilometres, covering Fukushima and four nearby prefectures.
The Kyodo news agency says the environment ministry has requested an additional 220 billion yen in its budget for the fiscal year from April 2012.