A Japanese duo who marketed charms said to glow for more than a decade ran out of luck themselves as it came to light that the products were radioactive, police said on Thursday.

The pair were based in Hiroshima, site of the world's first atomic attack, where they sold cellphone straps containing tritium, a radioactive substance that can be used in nuclear weapons.

Ichiro Shimozaki, a 40-year-old unemployed man, and Kyoko Fujii, a 45-year-old company worker, sold 5500 straps since 2004, earning 170 000 yen ($1620), a police spokesperson said.

They imported the tritium from Britain and sold the straps through a website, saying the charms would "shine for more than 10 years".

The straps contained 27 times more tritium than is allowed under the law, police said. Japan also requires people to inform the science ministry before commercialising any products with a radiation hazard.

However, the level of tritium is still believed to be unlikely to harm people wearing the straps, the science ministry said.

AFP