Nuclear and radioactive materials are still going missing and the information the United Nations atomic agency receives about such incidents may be the tip of the iceberg, said a senior U.N. official.

 

Any loss or theft of highly enriched uranium, plutonium or different types of radioactive sources is potentially serious as al Qaeda-style militants could try to use them to make a crude nuclear device or a so-called dirty bomb, experts say.

 

Khammar Mrabit, a director of the U.N.'s International Atomic Energy Agency (IAEA), said there had been progress in recent years to prevent that from happening. But he said more still needed to be done to enhance nuclear security.

 

The U.N. agency is helping states combat smuggling of uranium, plutonium or other items that could be used for a nuclear weapon or a dirty bomb, which uses conventional explosives to scatter radioactive material across a wide area posing health risks and massive cleanup costs.

 

About 150-200 cases are reported annually to the IAEA's Incident and Trafficking Database. More than 120 countries take part in this information exchange project, covering theft, sabotage, unauthorized access and illegal transfers.

 

While making clear that most were not major from a nuclear security point of view, Mrabit said some were serious incidents involving nuclear material such as uranium or plutonium.

 

These incidents mean that "material is still out of regulatory control", said Mrabit, who heads the nuclear security office of the IAEA. "Maybe this is the tip of the iceberg, we don't know, this is what countries report to us."