The United Nations' atomic watchdog hasn't been able to access data important to monitoring Iran's nuclear program since late February when the Islamic Republic started restricting international inspections of its facilities, the agency said Monday.

The International Atomic Energy Agency reported in a confidential document distributed to member countries and seen by The Associated Press that it has ``not had access to the data from its online enrichment monitors and electronic seals, or had access to the measurement recordings registered by its installed measurement devices'' since Feb. 23.

While the IAEA and Iran earlier acknowledged the restrictions limited access to surveillance cameras at Iranian facilities, Monday's report indicated they went much further. The IAEA acknowledged it could only provide an estimate of Iran's overall nuclear stockpile as it continues to enrich uranium at its highest level ever.

Iran started limiting inspections in a bid to put pressure on the government of U.S. President Joe Biden to lift crippling sanctions reimposed after then President Donald Trump pulled out of the 2015 nuclear deal with Iran unilaterally in 2018.

Under the deal, the IAEA placed around 2,000 tamper-proof seals on nuclear material and equipment. Those seals communicated electronically to inspectors. Automated measuring devices also provided real-time data from the program.

Talks are currently underway in Vienna for the U.S. to rejoin the deal, known as the Joint Comprehensive Plan of Action, or JCPOA.