The chief UN nuclear inspector declared that there was still "a lot of work" to be done on his return Wednesday from a trip to Iran, as the Tehran government confirmed his team visited no atomic sites.
Herman Nackaerts told reporters that his team had had a "good" visit which was organised in the wake of a damning report by the UN's atomic watchdog on Iran's nuclear ambitions and was planning to return soon.
"We had three days of intensive discussions about all our priorities. We are committed to resolving all the outstanding issues and the Iranians said they are committed too," Nackaerts said at Vienna airport.
"But of course there is still a lot of work to be done, and so we have planned another trip in the very near future," said Nackaerts, one of six-person International Atomic Energy Agency team to visit Iran.
"We had a good trip ... I will now go back to headquarters and inform the DG (IAEA director general Yukiya Amano) about the mission," he added, declining to comment further.
The visit took place against a backdrop of heightened tensions following the publication in November of an IAEA report that significantly raised suspicions Iran had done work on developing nuclear weapons.
The United States, the European Union and others have since ramped up sanctions to target Iran's oil industry and central bank. Tehran has threatened to close the Strait of Hormuz, a chokepoint for global crude shipments.
Iranian Foreign Minister Ali Akbar Salehi told the Fars news agency on Wednesday that the IAEA talks were "good" and that it was agreed to continue them in the future.
"The delegation had some questions about the alleged studies (in the November IAEA report), and thanks to God we had very good sessions," he was quoted as saying.
"They did not visit any nuclear sites. We were ready to facilitate such visits if they had wanted to."
The delegation also included IAEA number two Rafael Grossi, an Argentine, the IAEA's top legal official Peri Lynne Johnson, a US citizen, and two nuclear weapons experts, Jacques Baute of France and South African Neville Whiting.
Nackaerts had said before leaving that dialogue with Iran was long overdue.
The IAEA said in its November report that it had a trove of evidence that "indicates that Iran has carried out activities relevant to the development of a nuclear device."
It detailed 12 suspicious areas such as testing explosives in a steel container at a military base and studies on Shahab-3 ballistic missile warheads that the IAEA said were "highly relevant to a nuclear weapon programme."
Iran says that its nuclear programme is for peaceful purposes and the IAEA report was based on "forgeries" provided by its enemies.
The IAEA says however that Iran has a long history of being of breach of its obligations to declare nuclear facilities and materials and that the agency is unable to conclude all Tehran's activities are peaceful.
The last full talks between Iran and the so-called P5+1 -- the US, China, Russia, Britain, France and Germany -- broke down a year ago in Turkey.
Iran's President Mahmoud Ahmadinejad has insisted that Tehran is not dodging negotiations and was ready to sit down with world powers.
The six powers are however waiting for Tehran to reply to an October letter sent by EU foreign policy chief Catherine Ashton that stresses that discussions should focus on the "key question" of the Iranian nuclear issue.
The IAEA said in January that Iran had begun enriching uranium to 20-percent purity deep inside a mountain bunker at Fordo, taking it significantly closer to the 90-percent mark needed for a nuclear bomb.
At the same time, though, it has vowed to keep up cooperation with the IAEA.
Top US intelligence officials suggested Tuesday that military conflict with Iran was not inevitable, despite the soaring tensions.
James Clapper, Director of National Intelligence, told the US Senate Select Committee on Intelligence said that sanctions and diplomacy could still succeed in persuading Tehran to cooperate.
US President Barack Obama, who after being elected in 2008 declared he would extend a hand of friendship to Tehran, said in his State of the Union address last week that "a peaceful resolution" remained possible.