People found to be in possession of monazite are not likely to be charged for failing to store the low-level radioactive material safely because laws do not cover its storage, investigative sources said Friday.

Since mid-June, some 21 tons of monazite have been found at various locations in Tokyo, Ibaraki, Saitama, Chiba, Nagano, Gifu and Mie prefectures, and police have questioned Hiroshi Ikeda, 84, who heads an organization that is technically responsible for the material.

The level of radioactivity emitted by monazite can be harmful to humans.

A law originally covering nuclear reactor safety stipulates that a "user" of nuclear materials report their use to the prime minister.

But the law does not cover the storage, handling or transportation of such materials, and fails to clearly define the term "user," the sources told Kyodo News.

Ikeda, who used to run a trading company that handled tin and iron ore, extracted monazite more than 20 years ago from ore imported from Thailand, and sold it as specimens for nuclear fuel research, according to police sources.

Stored monazite was discovered after an acquaintance of Ikeda mailed a small amount of it to 10 locations, including the Prime Minister's Office, the Defense Agency and the Education Ministry, between June 6 and June 8.

A letter accompanying the monazite said one of Ikeda's colleagues in the organization, Nihon Bosei Bunka Kyokai (Japan Society of Motherhood and Culture), planned to smuggle the monazite to North Korea.