VIENNA - More still needs to be done to safeguard nuclear and radioactive materials given the scores of security incidents the UN atomic agency hears about each year, a senior official said on Wednesday.

Khammar Mrabit, a director of the UN International Atomic Energy Agency, said much had been achieved in the last decade to help make it harder for militants to carry out "malicious acts" involving potentially dangerous nuclear substances.

But, Mrabit told reporters ahead of next week's Nuclear Security Summit in South Korea: "Nuclear security is work in progress. Continuous improvement is a must. Complacency is bad."

"The agency continues to receive reports... which show that nuclear and other radioactive materials (are) still not properly secured. We have roughly around 200 incidents per year," said Mrabit, who heads the IAEA's Office of Nuclear Security.

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