Iran has let the UN's nuclear watchdog inspect one of the two sites it agreed last week to grant access to after a protracted standoff, while Tehran's stockpile of enriched uranium has risen further, quarterly reports by the agency said on Friday.
"Iran provided Agency inspectors access to the location to take environmental samples," according to an International Atomic Energy Agency (IAEA) report.
"The samples will be analysed by laboratories that are part of the Agency's network," it added.
An inspection at the second site will take place "later in September 2020 on a date already agreed with Iran", the report said.
Iran announced last week it would allow the IAEA access to the two sites, following a visit to Tehran by IAEA Director General Rafael Grossi.
Iran had denied the agency access earlier this year, prompting the IAEA's board of governors to pass a resolution in June urging Iran to comply with its requests.
Expanding stockpile of low enriched uranium
In a separate report also issued on Friday, the IAEA said Iran's stockpile of low enriched uranium (LEU) now stands at more than ten times the limit set down in the 2015 nuclear deal with world powers.
The limit was set at 300 kilogrammes (661 pounds) of enriched uranium in a particular compound form, which is the equivalent of 202.8 kg of uranium.
Measured against the latter figure, Iran's stockpile now stands at over 2,105 kg, the report said.
The stockpile, however, remains far below the many tonnes of LEU that Iran had accumulated before the 2015 deal.
Tehran is enriching up to a fissile purity of 4.5 percent, which while above the deal's 3.67 percent limit is still far short of the 20 percent higher-enriched level it achieved before the deal. Roughly 90 percent purity is considered weapons-grade, suitable for an atomic bomb.
The 2015 nuclear deal promised Iran economic incentives in return for the curbs on its nuclear program. President Donald Trump pulled the US out of the deal unilaterally in 2018, saying it needed to be renegotiated. Iran has since slowly violated the restrictions to try and pressure the remaining nations to increase the incentives to offset new, economy-crippling US sanctions.