The International Atomic Energy Agency says Iran is continuing to enrich uranium to up to 60 percent purity, a level far beyond limits set under the 2015 nuclear deal.
One of the latest IAEA reports on Iran's nuclear development program said Iran had an estimated 10 kilograms of uranium enriched to that level.
The level is far higher than the 3.67 percent purity limit set under the agreement.
The report also said one of four IAEA surveillance cameras installed at a centrifuge-related facility was destroyed and another severely damaged.
Under the 2015 deal, Iran agreed to restrict its nuclear activities in return for the lifting of sanctions.
The administration of former US President Donald Trump unilaterally withdrew Washington from the deal and re-imposed US sanctions against Iran.
Iran responded by proceeding with nuclear development in breach of the deal.
In April, the administration of US President Joe Biden began indirect talks with Iran in a bid to salvage the agreement, but the negotiations have stalled due to disagreements on issues including the extent of sanction relief.
The IAEA is expected to discuss Iran at its board meeting next week.