"I see security assurances provided by the US as part of the solution," ElBaradei, this year's Nobel peace prize winner, told reporters in Stockholm, two days after picking up his award in Oslo.

"I hope that as the negotiations with the European Union will resume that the US at some point will be more engaged," he said.

Iran said Sunday that a planned meeting later this month with Britain, France and Germany on its disputed nuclear programme will be decisive for the future of diplomacy over the crisis.

Foreign ministry spokesman Hamid Reza Asefi also reiterated that Iran would be sticking by its demand to conduct ultra-sensitive nuclear fuel work -- despite fears such activities could be diverted to make an atomic bomb.

North Korea in September agreed to to dismantle its nuclear weapons programme in return for economic and diplomatic benefits, after two years of negotiations.