Iran should reciprocate recent overtures by the Obama administration, Mohamed ElBaradei, chief of the International Atomic Energy Agency (IAEA), said on Monday.
"I have been telling my Iranian friends that they must reciprocate (the US opening)," he told a news conference. "I am very much supportive of the new approach and I hope it will work."
The IAEA is the United Nations' global nuclear regulator and it has wrestled with Tehran over its nuclear ambitions, especially its efforts to enrich uranium, which can be a route to making the fissile material for atomic weapons.
Iran says it is developing uranium enrichment technology for peaceful energy.