Supreme Leader Ayatollah Ali Khamenei said on Monday Iran might enrich uranium up to 60% purity if the country needed it and would never yield to US pressure over its nuclear programme, Reuters reported state media as saying.
Iran's 2015 nuclear deal with six powers, which it has been breaching since the United States withdrew in 2018, caps the fissile purity to which Tehran can refine uranium at 3.67%, well under the 20% achieved before the agreement and far below the 90% suitable for a nuclear weapon.
"Iran's uranium enrichment level will not be limited to 20%. We will increase it to whatever level the country needs … We may increase it to 60%," the TV quoted Khamenei as saying, upping the ante in a stand-off with US President Joe Biden's administration over the future of the fraying deal.
"Americans and the European parties to the deal have used unjust language against Iran … Iran will not yield to pressure. Our stance will not change," Khamenei said.
US State Department spokesman Ned Price said Khamenei's comments "sounds like a threat" and declined to respond to what he described as "hypotheticals" and "posturing".
He reiterated US willingness to engage in talks with Iran about returning to the 2015 nuclear deal.
The Biden administration said last week it was ready to talk to Iran about both nations returning to the accord abandoned by former US President Donald Trump.
Tehran said last week it was studying a European Union proposal for an informal meeting between current members of the deal and the United States, but has yet to respond to it.
Iran, which has resumed enriching to 20% in an apparent bid to heap pressure on the United States, has been at loggerheads with Washington over which side should take the initial step to revive the accord.
Although under domestic pressure to ease economic hardships worsened by sanctions, Iranian leaders insist Washington must end its punitive campaign first to restore the deal, while Washington says Tehran must first return to full compliance.