TOKYO: A radioactive substance that can be used to make a dirty bomb has been stolen in Japan, police and officials said on Tuesday, warning the public not to go near it.

A sealed metal container holding a small amount of iridium 192 was stolen on Monday from the office near Tokyo of a company that inspects industrial products, police said.

Iridium 192 is commonly used in cancer radiation treatment but it is also cited in scenarios by anti-terrorism investigators as an ingredient for a makeshift nuclear bomb.

Police said they did not know the motive of whoever stole the substance from the office of Non-Destructive Inspection Co. Ltd in the Tokyo suburb of Ichihara.

A security camera at the warehouse caught a person wearing a baseball cap and work tunic carrying away the 22-kilogramme (48.4-pound) container, the company and police said.

"We are examining the tape and looking for the person," a police spokesman said.

The science ministry issued a warning with a picture of the container, warning the public it was dangerous if opened.

"Anyone who finds it, please don't get near it. Report it to a nearby police station," the ministry said on its website.

The container held a two-millimetre (0.08-inch) tall cylindrical bit of iridium 192.

If taken out of the container, the stolen iridium 192 can give off 50 millisieverts of radiation an hour at a distance of one metre (3.3 feet), the limit for occupational radiation exposure for one year, the company said.

A normal person would start feeling sick, "just like when you have a hangover", if standing one metre in front of the opened container for five hours, said Toshio Kariya, a storage management official at the company.

Radiation could be fatal if a person is exposed to 7,000-8,000 millisieverts for a short period of time.

Non-Destructive Inspection, based in the western city of Osaka, uses devices such as iridium 192 to check for damages and defects in products without destroying them.


- AFP/so