President Barack Obama said on Saturday the discovery of a secret nuclear plant in Iran showed a "disturbing pattern" of evasion by Tehran which added urgency to its October 1. talks with world powers. Iranian officials voiced defiance, with one saying he hoped the plant, under construction south-west of Tehran, would soon be ready and "blind" Iran's enemies and another expressing shock that the world was not grateful it had revealed its existence.
Iran, which insists its nuclear programme is aimed at electricity generation rather than weapons production as feared by the West, will meet the United States and five other powers in the Swiss city of Geneva on Thursday. The US president warned Iran on Friday it would face "sanctions that bite" if it did not come clean.
"This is a serious challenge to the global non-proliferation regime and continues a disturbing pattern of Iranian evasion," he said on Saturday. "That is why international negotiations with Iran scheduled for October 1 now take on added urgency," Obama said in his weekly radio and Internet address on Saturday.
Britain, France and Germany have joined the United States in raising the prospect of new sanctions against Iran if it does not take steps to allay concerns about its nuclear programme. Russia also signalled a greater willingness to go along with sanctions while China said it favoured a "dual track" approach of pressure and talks. UN Secretary General Ban Ki-moon expressed "grave concern" in talks with Iranian President Mahmoud Ahmadinejad on Friday and said Tehran had to show its intentions were peaceful.
"He emphasised that the burden of proof is on Iran," Ban's press office said in a statement. Adding to the tension, Iranian media said Iran's elite Revolutionary Guards would hold missile defence exercises starting on Sunday and taking place over several days.