While 60 percent enrichment is higher than any level Iran previously enriched uranium, it is still lower than weapons-grade levels of 90 percent. The 2015 nuclear deal limited Iran’s enrichment to 3.67 percent.
Iran has begun 60 percent uranium enrichment at its Natanz plant, the country's nuclear chief said, days after an explosion at the site that Tehran blamed on Israel.
The move is likely to raise tensions even as Iran negotiates in Vienna over a way to allow the US back into the agreement and lift the crushing economic sanctions it faces. However, its scope also provides Iran with a way to quickly de-escalate if it chooses.
"We are producing about nine grams of 60 percent enriched uranium an hour," Ali Akbar Salehi, head of the Atomic Energy Organisation of Iran, said on Friday. "But we have to work on arrangements to drop it to 5 grams per hour."
Salehi said the centrifuges now produce 9 grams an hour, but that would drop to 5 grams an hour in the coming days.
Earlier, parliament speaker Mohammad Qalibaf said Iranian scientists had successfully started enriching 60 percent uranium at 12:40 am local time (0810 GMT).
"The will of the Iranian nation makes miracles that thwart any conspiracy," Qalibaf said on Twitter.
The International Atomic Energy Agency, which monitors Iran's nuclear program, did not immediately respond to a request for comment. Earlier this week, it sent its inspectors to Natanz and confirmed Iran was preparing to begin 60 percent enrichment at an above-ground facility at the site.
The announcement also marks a significant escalation after the attack this past weekend that damaged centrifuges at Natanz that is suspected of having been carried out by Israel. While Israel has yet to claim it, it comes amid a long-running shadow war between the two Mideast rivals.
Iran has said its decision to increase enrichment to its highest level ever was in response to sabotage at Natanz.
READ MORE: Iran: 60% uranium enrichment response to Israel's Natanz attack
Salvaging a fractured deal
Iran and global powers are meeting in Vienna to try to rescue a 2015 nuclear deal abandoned by Washington three years ago, in an effort potentially complicated by Tehran’s decision to ramp up uranium enrichment.
READ MORE: Iran: Natanz sabotage could hurt Vienna nuclear deal talks
The 2015 agreement sought to make it harder for Iran to develop an atomic bomb – something it denies ever trying to do – in return for lifting sanctions.
Abbas Araqchi, Iran’s chief nuclear negotiator in Vienna, said earlier this week that Iran would activate 1,000 advanced centrifuge machines at Natanz.
An Iranian official told Reuters that "60 percent enrichment will be in small quantity" only.
Iran insists its nuclear program is peaceful, though the West and the IAEA say Tehran had an organised military nuclear program up until the end of 2003.
An annual US intelligence report released on Tuesday maintained the American assessment that “Iran is not currently undertaking the key nuclear weapons-development activities that we judge would be necessary to produce a nuclear device.”
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Iran previously had said it could use uranium enriched up to 60 percent for nuclear-powered ships. However, the Islamic Republic currently has no such ships in its navy.
The threat of higher enrichment by Iran already had drawn criticism from the US and three European nations in the deal – France, Germany and the United Kingdom. On Friday, European Union spokesperson Peter Stano called Iran's decision “a very worrisome development.”
"There is no credible explanation or civilian justification for such an action on the side of Iran,” Stano said. The Vienna talks aim to “make sure that we go back from such steps that bring Iran further away from delivering on its commitments and obligations”