The head of the U.N. nuclear agency warned Monday of the dangers of nuclear material falling into the hands of terrorists and urged world nations to apply an agreement meant to minimize such dangers.

Two-thirds of the 89 countries agreeing with the Amendment to the Convention on the Physical Protection of Nuclear Material must ratify it for it to enter into force. Yukiya Amano of the International Atomic Energy Agency says ratification by 11 more nations is needed.

Its application would “reduce the likelihood of terrorists being able to detonate a …’dirty bomb,'” which can spread radioactivity over a wide area and also reduce the risk of an attack on a nuclear power plant, said Amano.

He noted that nearly 2,800 incidents of radioactive material going missing have been reported to his agency since 1995.

Some are of serious concern. Moldovan police working with the FBI last year stopped four attempts by smugglers to sell nuclear material to extremists in the Middle East over the past five years. In one instance a year ago, undercover agents were offered a large amount of radioactive cesium.

In the most recent reported case, the agency said last week that it had been informed by Iraq of the theft of an industrial radiography device in the city of al-Zubair in November.

Experts say the amount of the substance is too small to pose a terrorist threat. But if mismanaged, it could be fatal on exposure over several days, or in some cases as little as a few hours.

(AP)