"Now the first team of IAEA inspectors is back in Iran, and we are about to restart," International Atomic Energy Agency (IAEA) director general Grossi said.
Grossi, who was in Washington DC for the annual meeting of the Institute of Nuclear Materials Management, stopped short of saying there was an agreement or timeline for them to resume their work.
"When it comes to Iran, as you know, there are many facilities. Some were attacked, some were not. So we are discussing what kind of modalities, practical modalities, can be implemented in order to facilitate the restart of our work there."
Resuming full cooperation with the IAEA is one of the conditions three European countries - Germany, Britain and France - have put forward to Iran as a deadline for their triggering of UN sanctions at the end of August looms.
Under UN Security Council Resolution 2231, all sanctions lifted under a 2015 nuclear deal could automatically be reimposed if one party accuses Iran of non-compliance.
Tehran argues that the European countries no longer have legal standing to trigger the measure and has rejected the legitimacy of such a move.
"The reconstruction of (US-Iran) dialogue, conversation is more difficult, but it's not impossible. It's not at all impossible," Grossi added.
"Our work, the work of the inspectors, is indispensable, because without us in there checking what is going on, you cannot enter any serious negotiation without knowing what is really happening in countries."
Hardline opposition to IAEA work
The Iranian parliament's National Security and Foreign Policy Commission issued a statement on Tuesday expressing distrust of the IAEA ahead of the inspectors' return.
Iran would demand conditions such as “full respect for the national sovereignty and territorial integrity of the Islamic Republic of Iran” in order to cooperate with the agency in any form, the statement asserted.
Iran’s Foreign Minister said earlier this month that the IAEA must clarify how it would go about inspecting nuclear facilities bombed by Israel and the United States in June.
Following US strikes on Iranian nuclear sites on June 22, Iran passed a law suspending cooperation with the IAEA under its safeguards agreement unless its security demands are met.
Grossi gets 24/7 protect over Iran threat
Grossi has been under round-the-clock protection in recent weeks following a specific Iranian threat, The Wall Street Journal reported on Tuesday citing informed sources.
"The elite unit of Austria’s security services is protecting Grossi after the country’s intelligence agency received information of a threat to the International Atomic Energy Agency chief from a third party," the report said citing one source.
In July, deputy head of Iran’s judiciary said the country may try Grossi in absentia over his alleged role in enabling attacks on the country’s nuclear facilities.
A hardline Iranian newspaper even called for Grossi’s arrest and execution, accusing him of acting as an Israeli agent.
Britain, France and Germany condemned those threats at the time and expressed full support for Grossi and the IAEA in fulfilling its mandate.