A handout picture released by Iran's Atomic Energy Organization on Nov 6, 2019, shows the interior of the Fordow Uranium Conversion Facility in Qom, in the north of the country. (HO / ATOMIC ENERGY ORGANIZATION OF IRAN / AFP

VIENNA - Iran has told the United Nations nuclear watchdog it plans to enrich uranium to up to 20 percent purity, a level it achieved before its 2015 accord, at its Fordow site buried inside a mountain, the agency said on Friday.

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The move is the latest of several recent announcements by Iran to the International Atomic Energy Agency that it plans to further breach the deal, which it started violating in 2019 in retaliation for Washington’s withdrawal from the agreement and the reimposition of US sanctions against Tehran.

Iran has breached the deal’s 3.67 percent limit on the purity to which it can enrich uranium, but it has only gone up to 4.5 percent so far, well short of the 20 percent it achieved before the deal and the 90 percent that is weapons-grade

This step was one of many mentioned in a law passed by Iran’s parliament last month in response to the killing of the country’s top nuclear scientist, which Tehran has blamed on Israel. Such moves by Iran could complicate efforts by US President-elect Joe Biden to rejoin the deal.

“Iran has informed the Agency that in order to comply with a legal act recently passed by the country’s parliament, the Atomic Energy Organization of Iran intends to produce low-enriched uranium (LEU) up to 20 percent at the Fordow Fuel Enrichment Plant,” the IAEA said in a statement.

“Iran’s letter to the Agency ... did not say when this enrichment activity would take place,” the IAEA statement said.

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Fordow was built inside a mountain, apparently to protect it from aerial bombardment, and the 2015 deal does not allow enrichment there. Iran is already enriching at Fordow with first-generation IR-1 centrifuges.

Iran has breached the deal’s 3.67 percent limit on the purity to which it can enrich uranium, but it has only gone up to 4.5 percent so far, well short of the 20 percent it achieved before the deal and the 90 percent that is weapons-grade.

The deal’s main aim was to extend the time Iran would need to produce enough fissile material for a nuclear bomb, if it chose to, to at least a year from roughly two to three months. It also lifted international sanctions against Tehran.