The head of the International Atomic Energy Agency (IAEA) Rafael Grossi will visit Iran Friday for high-level meetings, the semi-official Fars news agency reported Wednesday.

The visit comes amid discussions with Tehran on the origin of uranium particles enriched to up to 83.7% purity, very close to weapons grade, at its Fordow enrichment plant, a report by the watchdog seen by Reuters confirmed on Tuesday.

Iran has rejected the claims of enrichment up to that level.

Iran began violating the 2015 nuclear deal’s (JCPOA) enrichment limit set at 3.67 percent in 2019 when the Trump administration imposed full oil export sanctions, but until the Biden administration came to office higher enrichment had stayed at around 5 percent.

The head of Iran’s Atomic Energy Organization, Mohammad Eslami, said on Wednesday that the Islamic Republic's production is at 60 percent according to state media.

Iranian officials have been insisting that a few particles are sometimes enriched beyond set limits, but the quantity is negligible. Eslami repeated the same argument on Wednesday. It is not clear if the IAEA agrees with this explanation.

The UN watchdog has been demanding other explanations from Tehran about its secret nuclear work before 2003 and so far there has been no resolution.

Talks to revive the JCPOA reached an impasse last September while Iran continues to stockpile 60-percent enriched uranium. It is estimated that it can reach weapons grade enrichment in a matter of weeks and can produce four nuclear warheads.