VIENNA Reuters - 

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 UN 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 UN’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.“You have to improve continuously because also on the other side, the bad guys, they are trying to find ways how to evade such detection,” Mrabit said in an interview.“The threat is global because these people operate without borders,” he said on Thursday before an IAEA-hosted meeting of more than 100 states in Vienna next week on how to ensure nuclear materials do not fall into the wrong hands.The UN 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.”Meanwhile, Iran will press ahead with its uranium enrichment programme, its nuclear energy chief said on Friday, signalling no change of course despite the victory of a relative moderate in the June 14 presidential election.Fereydoun Abbasi-Davani, head of the Islamic Republic’s Atomic Energy Organisation, said production of nuclear fuel would “continue in line with our declared goals. The enrichment linked to fuel production will also not change.”Speaking through an interpreter to reporters at a nuclear energy conference in St Petersburg, Russia, he said work at Iran’s underground Fordow plant - which the West wants Iran to close - would also continue. Iran refines uranium at Fordow that is a relatively close technical step away from weapons-grade.Iran says it is enriching uranium to fuel a planned network of nuclear energy power plants, and also for medical purposes.But enriched uranium can also provide the fissile material for nuclear bombs if processed further, which the West fears may be Tehran’s ultimate goal.Abbasi-Davani said Iran’s so far only nuclear power plant - which has suffered repeated delays - had been “brought back online” three days ago and was working at 1,000 megawatt capacity. A UN nuclear agency report said in May that the Russian-built Bushehr plant was shut down, giving no reason.“Thankfully in the last days, no concrete defects with the plant have been reported to me,” Abbasi-Davani said.Hopes for a resolution to the nuclear dispute were boosted this month with the election as president of Hassan Rouhani, who has promised a more conciliatory approach to foreign relations than confrontational predecessor Mahmoud Ahmadinejad. Rouhani will take office in early August.As chief nuclear negotiator under a reformist president between 2003 and 2005, Rouhani struck a deal with European Union powers under which Iran temporarily suspended uranium enrichment activities. The work restarted after Ahmadinejad was first elected and has been sharply expanded.Iran’s theocratic supreme leader, Ayatollah Ali Khamenei, said on Wednesday the nuclear stand-off could easily be resolved if the West were to stop being so stubborn.The hardline Khamenei wields ultimate control over Iranian nuclear policy, although the president exerts some influence.While accusing the West of being more interested in regime change than ending the dispute, Khamenei did express a desire to resolve an issue which has led to ever tighter and more damaging sanctions on Iran’s oil sector and the wider economy.But analysts say it remains highly uncertain whether Iran may now be more prepared to meet the demands of world powers that it immediately halt its most sensitive enrichment, to a fissile concentration of 20 percent, and stop work at Fordow.Asked whether there would be any change in Iranian policy after Rouhani’s election and whether it could suspend 20 percent enrichment, Abbasi-Davani said Iran’s nuclear programme was aimed at producing electricity and for medical purposes.“In line with these two goals of course the production of energy will not stop,” he said.Fordow is under the monitoring of the UN’s International Atomic Energy Agency, he said. “So in line with our declared plans ... we will of course continue our work at this centre.”Iran will soon hand over to the Vienna-based IAEA a list with plans for new nuclear reactor sites, he said, speaking in front of a model of the Bushehr reactor at the Islamic state’s stand at the nuclear industry fair in St Petersburg.