Iranian President Hassan Rouhani said Wednesday its decision to boost uranium enrichment to 60 percent was a response to Israel's "terrorism," days after saboteurs attacked the Natanz nuclear facility.
"Enabling IR-6 (centrifuges) at Natanz today, or bringing enrichment to 60 percent: this is the response to your malice," Rouhani said in a message aimed at arch-enemy Israel, in televised remarks.
"What you did was nuclear terrorism. What we do is legal," he said, referring to a blast early Sunday that knocked out electricity at its main nuclear facility in central Iran.
Iran's envoy to the International Atomic Energy Agency, Kazem Gharibabadi, wrote on Twitter that enrichment to higher purity was starting and that "we expect to accumulate the product next week" from centrifuges at Natanz.
Iran's announcement of stepped-up enrichment, made Tuesday, has cast a shadow over talks in Vienna aimed at salvaging the tattered 2015 nuclear deal between Iran and world powers that then US president Donald Trump abandoned three years ago.
"You wanted to make our hands empty during the talks but our hands are full," Rouhani said Wednesday.
The new step will bring Iran closer to the 90 percent purity threshold for military use and shorten its potential "breakout time" to build an atomic bomb.
Under the nuclear deal, Iran had committed to keep enrichment to 3.67 percent, though it had stepped this up to 20 percent in January.
Gharibabadi said in his tweet that the new material "will improve significantly both the quality and quantity of radiopharmaceutical products".
He wrote the enrichment would be handled by only two cascades of IR-4 and IR-6 centrifuges at Natanz. A cascade is a group of centrifuges working together to enrich uranium more quickly.
Israel is strongly opposed to US President Joe Biden's efforts to revive the nuclear agreement between Iran and the UN Security Council's permanent members plus Germany.
The accord, agreed when Biden was vice president to Barack Obama, promised Tehran relief from punishing sanctions in return for agreeing to limits on its nuclear program.
The United States said Tuesday it stood by Israel but remained committed to the Iran talks despite Tehran's enrichment plan.
Rouhani in his comments Wednesday insisted Iran still seeks a negotiated settlement in Vienna over its program.
"The US should return to the same conditions of 2015 when we signed the nuclear deal,” Rouhani said.