Washington told Tehran on Tuesday that it must let the UN atomic agency continue to monitor its activities, as they agreed on, or put wider talks on reviving the Iran nuclear deal at risk, Reuters reported.
The International Atomic Energy Agency and Iran reached a three-month agreement in February on IAEA’s monitoring of the country’s activities.
Under that agreement, data will be collected in a black-box-type arrangement, and IAEA will only be able to access it at a later date.
"We strongly encourage Iran to avoid any action that would prevent the collection of or IAEA access to the information necessary for it to quickly re-establish ... continuity of knowledge," a US statement to a meeting of the International Atomic Energy Agency's 35-nation Board of Governors said.
"Such action would, at a minimum, seriously complicate ongoing efforts to reach an understanding on how Iran can return to compliance with its JCPOA commitments in return for a similar U.S. resumption," it added, referring to the 2015 deal by its full name, the Joint Comprehensive Plan of Action.
Negotiations have been underway since April in the Austrian capital between Iran and the remaining members of the accord— Britain, China, France, Germany and Russia— to revive the 2015 nuclear deal abandoned by Donald Trump in 2018.
US diplomats have participated indirectly in the talks from a nearby hotel.