International Atomic Energy Agency chief Dr Mohamed ElBaradei has urged Iran to improve international confidence in its peaceful intentions by opening up its nuclear programme to closer inspections.
"I think it is necessary for Iran to have maximum transparency and through this maximum transparency to create trust," Dr ElBaradei told reporters following a meeting with Iran's Foreign Minister Kamal Kharrazi.
Dr ElBaradei is expected to press Iranian officials during his one-day trip to sign up to the IAEA's Additional Protocol which would allow more intrusive, short-notice inspections.
Diplomats in Tehran say there appears to be a lively debate going on within Iran's political establishment on whether to agree to the tougher inspection regime with some signs that Iran may be moving closer to signing the Additional Protocol.
"Reading between the lines, it seems like they may be preparing the ground to sign," said one European diplomat.
Sandwiched between Iraq and Afghanistan, Iran is conscious that failure to address concerns about its nuclear ambitions could increase pressure from Washington and jeopardise relations with other countries, diplomats say.
The European Union has warned Iran a potential trade deal depends on greater transparency over its atomic programme. Japan has put a $2 billion oil deal on hold over the nuclear concerns.
Iran insists it has no desire to make nuclear weapons. But it has so far refused to sign the IAEA's Additional Protocol until an international embargo on the export of nuclear technology to Iran is scrapped.