The International Atomic Energy Agency says Iran has stored most of its highly enriched uranium in a complex of underground tunnels at its Isfahan facility.

Iran has stored much of its highly enriched uranium in an underground tunnel complex at its Isfahan facility, the U.N. nuclear watchdog said in a report, urging Tehran to allow inspections The pressure is getting bigger U.S. dissatisfaction with its nuclear program.

An International Atomic Energy Agency (IAEA) report circulated to member states on Friday confirmed earlier findings that the country enriched uranium to 60%, just one step away from weapons-grade purity, raising concerns that the IAEA does not have access to the Isfahan base, one of three facilities claimed by the United States.obliterated” In last year’s 12 days of war.

The IAEA report also noted that its inspectors do not know the exact location of a fourth uranium enrichment facility that Iran says it established in Isfahan before the 12-day war, adding that they do not know its operating status or whether it currently contains nuclear material.

The IAEA said it had observed in satellite images “regular vehicle activity around the entrance to the Isfahan tunnel complex, which stores U-235 enriched to 20% and 60%…” and stressed the importance of being able to carry out inspections in Iran without further delay.

Iran had no immediate comment.

The report comes a day after U.S. and Iranian negotiators held talks third round Indirect talks brokered by Oman in Geneva failed to yield any breakthrough.

The IAEA’s 35-nation board will discuss the issue at its quarterly meeting in Vienna next Monday, while Oman holds further meetings between technical teams in the same city.

There is uncertainty over the fate of more than 400 kilograms (882 pounds) of 60% enriched uranium stored in Iran, which nuclear regulator inspectors last saw on June 10 last year.

Later that month, Israel launched an attack on Iran, beginning a 12-day war in which the United States briefly joined in bombing Iran’s nuclear facilities.

Tehran has suspended some cooperation with the International Atomic Energy Agency and restricted the agency’s inspectors’ access to sites bombed by Israel and the United States, accusing the U.N. agency of bias and failure to condemn the attacks.

Al Jazeera’s Ali Hashim said the technical points discussed in Monday’s Oman-mediated talks would be “relevant” to the extraction of 440.9 kilograms (972 pounds) of enriched uranium reported by the International Atomic Energy Agency ahead of the 12-day war, in case “there is any tendency to weaponize the program.”

However, Hashim added that the IAEA realized that “even the Iranians do not have access to these facilities.” “So a lot of work has been done around these facilities, at least that’s what the satellite images show, but the Iranians don’t seem to have access,” he said.

Al Jazeera’s Tohid Assadi reported from Tehran that enriched uranium stockpiles and inspections are the main “crux” in discussions between the United States and Iran.

After yesterday’s talks, Iranian Foreign Minister Araghchi said the United States should stop its “excessive demands.” He did not specify what those demands were, but the United States said it wants Iran to completely dismantle its nuclear infrastructure, limit its ballistic missile arsenal and stop supporting regional allies.