UN nuclear watchdog head Rafael Grossi arrived late Saturday in Iran for talks on the eve of Tehran's deadline for US sanctions to be lifted, as President Joe Biden called for "careful diplomacy".
The deadline, set by Iranian lawmakers, carries the threat of a suspension of some nuclear inspections, stoking international concern about a possible expulsion of UN inspectors. But Iran has stressed it will not cease working with the International Atomic Energy Agency (IAEA) or expel its inspectors.
Grossi was received in Tehran by Iran's ambassador to the IAEA, Kazem Gharibabadi, and Iran Atomic Energy Organisation official Behrouz Kamalvandi, Gharibabadi tweeted Saturday evening. The IAEA chief's visit is due to run into Sunday.
On Friday, Grossi tweeted he would "meet with senior Iranian officials to find a mutually agreeable solution, compatible with Iranian law, so that the @iaeaorg can continue essential verification activities in Iran".
"Looking forward to success -- this is in everybody's interest," he added.
Iran has notified the IAEA that it will suspend "voluntary transparency measures", notably inspection visits to non-nuclear sites, including military sites suspected of nuclear-related activity, if the United States has not lifted the sweeping sanctions former president Donald Trump reimposed in 2018.
The new measures, laid out in a law passed by the conservative-dominated parliament in December, are to go into effect on Tuesday, the head of Iran's atomic body, Ali Akbar Salehi, confirmed on Saturday.
As Iran implements the law and "the other side has not yet fulfilled its obligations to lift the sanctions, inspections beyond safeguard measures will be suspended", state television quoted Salehi as saying on its website.
He added that "during tomorrow's (Sunday) meeting with Mr. Grossi, the IAEA's considerations in the framework of the safeguards agreement and bilateral cooperation will be reviewed and discussed".
Tehran has repeatedly said it is ready to return to its nuclear commitments on the condition that Washington does so first by lifting the sanctions reimposed by Trump that have dealt a heavy blow to Iran's economy.
Following an offer for talks by the Biden administration, Foreign Minister Mohammad Javad Zarif tweeted Friday that Iran would "immediately reverse" its retaliatory measures if the US lifts "all sanctions imposed, re-imposed or re-labelled by Trump".