Iran has continued to increase its stockpile of highly enriched uranium that could be used to make nuclear weapons in contravention of a 2015 accord with world powers that was meant to contain Tehran’s nuclear program, the U.N. atomic watchdog said Tuesday.

The International Atomic Energy Agency also told member states in its confidential quarterly report that its verification and monitoring activities have been “seriously undermined” since February by Iran’s refusal to let inspectors access IAEA monitoring equipment.

The Vienna-based agency told members that its confidence in properly assessing Iran’s activities — what it called the “continuity of knowledge” — was declining over time and that would continue “unless the situation is immediately rectified by Iran.”

The IAEA said certain monitoring and surveillance equipment cannot be left for more than three months without being serviced. It was provided with access this month to four surveillance cameras installed at one site, but one of the cameras had been destroyed and a second had been severely damaged, the agency said.

Its director-general, Rafael Mariano Grossi, said he was willing to travel to Iran to meet the recently elected government for talks on the issue.

The agency said it estimates Iran’s stock of uranium enriched to up to 60% fissile purity at 10 kilograms, an increase of 7.6 kilograms since May, while the country’s stockpile of uranium enriched to up to 20% fissile purity is now estimated at 84.3 kilograms, up from 62.8 kilograms three months earlier.

Iran’s total stock of uranium is estimated at 2,441.3 kilograms as of Aug. 30, down from 3241 kilograms on May 22, the agency said.

Tehran is only permitted to stockpile 202.8 kilograms of uranium under the nuclear deal known as the Joint Comprehensive Plan of Action, or JCPOA, which promises Iran economic incentives in exchange for limits on its nuclear program, and is meant to prevent Tehran from developing a nuclear bomb.

The U.S. unilaterally pulled out of the nuclear deal in 2018 under then-President Donald Trump, but Britain, France, Germany, China and Russia have tried to preserve the accord.

Tehran’s strategy of deliberately violating the deal is seen as an attempt to pressure Europe to give Iran incentives to offset the crippling American sanctions re-imposed after the U.S. pullout.

President Joe Biden has said he is open to rejoining the pact. The last round of talks in Vienna ended in June without a clear result.

In Tehran, Iranian news agencies quoted Iran’s envoy to the IAEA, Kazem Gharibabadi, as saying in Vienna that all Iran’s nuclear activities had been “carried out in the framework of Iran’s nuclear rights and under nonproliferation treaty.”

He claimed the agency was under pressure by some members and urged it to remain “independent, impartial and professional.”

In a separate confidential report seen by The Associated Press, the agency expressed its deep concern at the presence of nuclear material at undeclared locations in Iran. “Even after some two years, the safeguards issues (...) in relation to the four locations in Iran not declared to the agency remain unresolved,” the report stated.

___

Nasser Karimi in Tehran contributed to this report.

Associated Press