Open this photo in gallery

       The Iranian flag waves in front of the International Atomic Energy Agency (IAEA) headquarters in Vienna on May 23, 2021.

       Leonhard Foeger/Reuters

       Iran has given notice of concrete steps to produce uranium metal enriched to up to 20% purity for reactor fuel, the U.N. atomic watchdog said on Tuesday, describing a move that is likely to anger Western powers in talks to revive the Iran nuclear deal.

       Iran has been in indirect talks with the United States since April to revive the 2015 deal, which former U.S. President Donald Trump abandoned. The deal imposed curbs on Iran’s nuclear programme in return for the lifting of sanctions, and after Trump withdrew, Iran began violating many of its restrictions.

       Tehran has already produced a small amount of uranium metal this year that was not enriched. That is a breach of the deal, which bans all work on uranium metal since it can be used to make the core of a nuclear bomb.

       Iran has outlined plans to produce enriched uranium metal, saying it is developing fuel for its Tehran Research Reactor, but Washington and its European allies dispute Tehran’s intentions and have called on it to stop.

       “Today, Iran informed the Agency that UO2 (uranium oxide) enriched up to 20% U – 235 would be shipped to the R&D laboratory at the Fuel Fabrication Plant in Esfahan, where it would be converted to UF4 (uranium tetrafluoride) and then to uranium metal enriched to 20% U – 235, before using it to manufacture the fuel,” an International Atomic Energy Agency statement said.

       Summarising a report to its member states, the IAEA described the plan as a “multi-stage process”, suggesting it will take time before the enriched metal is produced.

       The report is likely to increase tensions in the talks, which include the other parties to the 2015 deal. The talks adjourned on June 20 and a date for their resumption has not yet been set.

       “This is clearly an escalation – clearly another message by Iran that in the absence of any restoration of (the nuclear deal), they are going to continue ramping up their capability and their pressure,” said Bob Einhorn, a nonproliferation expert at the Brookings Institution think tank.

       The United States on Tuesday called Iran’s decision to produce uranium metal enriched to 20% purity an “unfortunate step backwards” but said the window for diplomacy to allow both to resume compliance with the 2015 nuclear deal remained open.

       “It is worrying that Iran chooses to escalate its non-performance of its (nuclear deal) commitments, especially with experiments that have value for nuclear weapons research. It’s another unfortunate step backwards for Iran, particularly when we for our part have demonstrated our sincere intention and willingness to return to the (deal),” U.S. State Department spokesman Ned Price told reporters at a briefing.

       Story continues below advertisement

       Britain, France and Germany said on Tuesday they had “grave concern” about Iran’s decision to give notice it would take concrete steps to produce uranium metal enriched to up to 20% purity for reactor fuel.

       “Iran has no credible civilian need for uranium metal R&D and production, which are a key step in the development of a nuclear weapon,” the three countries said in a joint statement issued by Britain’s foreign ministry.

       “We strongly urge Iran to halt all activities in violation of the JCPOA, without delay and to return to the negotiations in Vienna with a view to bringing them to a swift conclusion,” the three countries added.

       Our Morning Update and Evening Update newsletters are written by Globe editors, giving you a concise summary of the day’s most important headlines. Sign up today.