Australian nuclear experts working to prevent a "dirty bomb" attack by terrorists have found large unsecured sources of dangerous radioactive material in southeast Asia, a report said Monday.
A team from the Australian Nuclear Science and Technology Organisation (ANSTO) discovered enough loose material to contaminate the heart of a major city, the Australian newspaper reported.
At one site a "substantial" piece of cobalt used for cancer therapy had been found abandoned after a radiation centre was closed.
A conventional bomb wrapped around a small stick of cobalt could contaminate a large area of a city, dramatically boost cancer rates and force residents out for decades, scientists say.
"There are two countries where we have located quite large sources," ANSTO's chief of operations, Ron Cameron, told the paper. He declined to identify the countries until the material had been properly secured.
About 25 other radiation centres were also being investigated in a third country, he said.
The ready availability of loose radioactive material suitable for dirty bombs had been a concern of Australia for the past year, and officials had been working with US experts to locate and secure it, Cameron said.
"The system is only as strong as the weakest link. If there's an area of the world where terrorists can get hold of the material then that's where they'll go," he said.
Secure storage areas had been built and systems created to track, control and secure radioactive material left over from medical and industrial use.
The Federation of American Scientists told the US Senate in 2002 that a dirty bomb using a single stick of radioactive cobalt about an inch (2.54 cm) in diameter and a foot (30 cm) long could sharply increase the risk of cancer in an area covering 300 city blocks for 40 years.
"It would be decades before the city was inhabitable again, and demolition might be necessary," the scientists said.
Concern that Australia, which has troops in Iraq, could be a target for a terrorist attack has risen sharply since the London bombings in July, and the government is considering tougher counter-terrorism legislation and security measures.