Iran has not yet provided a "final answer" to a "unique" international nuclear fuel offer, Mohamed ElBaradei, the outgoing head of the UN nuclear watchdog, said on Friday.
"I do not consider that I have received a final answer," ElBaradei, chief of the International Atomic Energy Agency (IAEA), said in Berlin. "But I also very much hope that I will get an answer pretty much soon."
"We have not received any written response from Iran. What I got of course is an oral response, which basically said 'we need to keep all the material in Iran until we get the fuel,'" he said. "That to me is a case of extreme mistrust."
He added: "I believe that frankly the ball is very much in the Iranian court. I hope that they will not miss this unique and fleeting opportunity."
In an attempt to draw Iran into talks and guarantee that its nuclear ambitions are peaceful, six world powers have offered to reprocess some of its low-enriched uranium abroad.
But on Wednesday, Iran appeared to reject the proposal out of hand, prompting US President Barack Obama to warn of "consequences" in the form of toughened sanctions.
Representatives from the six powers -- the United States, China, Russia, Britain, France and Germany -- were meeting in Brussels on Friday to discuss the next steps in what ElBaradei called "an environment of desperation."