The international nuclear watchdog said Iran’s stocks of 60% enriched uranium have increased to over 400 kilograms. It also criticized Iran for a “lack of cooperation.”

The UN’s International Atomic Energy Agency (IAEA) said that Iran has increased its production of enriched uranium in recent months, according to a report seen by multiple news agencies on Saturday.

The news comes amid talks between Iran and the US aimed at curtailing Tehran’s nuclear program and preventing it from acquiring nuclear weapons.