The president of the Iranian Atomic Energy Organization, Mohammad Reza Aghazadeh, admitted Friday that Iran has built underground tunnels to use as deposits for nuclear material. "Right now we have 250 tons of Uf6 (the gas obtained by treating mineral uranium, which is transformed into enriched uranium by inserting it in centrifuges connected to a cascade) deposited in a network of underground tunnels which can't be found anywhere else in the world," he said. "Each month we put new material and machines worth millions of dollars in these tunnels, as well as in our nuclear installations," Aghazadeh added.On 23 December, the Security Council voted unanimously to impose sanctions on Iran over its nuclear programme, which the international community fears is aimed at building atomic weapons. Iran denies this, insisting its programme is solely for civilian use. The resolution bans trade with Iran in all items, materials, equipment, goods and technology which could contribute to such activities or to the development of nuclear weapon delivery systems. States are also required to prevent the provision to Iran of any technical assistance or training, financial assistance, investment, brokering or other services. Iran plans to begin production of nuclear fuel on an industrial scale soon, the country's official news agency IRNA quoted Ahmadinejad as saying on Wednesday.