Iran says it has injected uranium gas into centrifuges at its Fordow nuclear site as Tehran further moves away from complying with its 2015 nuclear deal with world powers.
Iran's atomic energy agency early on November 7 said in a statement posted on its website that "production and collection of enriched uranium at the Fordow site has started."
The statement came after a spokesman for the agency said the night before that "in the coming hours, the process of injecting [uranium-hexafluoride] gas into the centrifuges at the Fordow site will be finalized in the presence of inspectors" from the International Atomic Energy Agency (IAEA).
The spokesman, Behrouz Kamalvandi, was quoted by the semiofficial news agency ISNA as saying the "production" of enriched uranium would be "operational from midnight."
A spokesman for the UN nuclear agency said IAEA inspectors "are on the ground in Iran and will report any relevant activities to IAEA headquarters in Vienna." The agency said it would hold an extraordinary board meeting on Iran in Vienna on November 7.
Hours earlier, President Hassan Rohani wrote on Twitter that "Thanks to U.S. policy and its allies, Fordow will soon be back to full operation."
Separately, diplomats familiar with IAEA activities in the country told Reuters that Iranian authorities had briefly detained an inspector working for the nuclear watchdog at the Natanz enrichment site last week and seized her documents.
The 2015 nuclear deal allows for 130-150 inspectors from the agency to be designated for Iran.
An IAEA spokesman and Iran's envoy to the IAEA declined to comment on the report.
Rohani announced on November 5 that uranium gas would start being injected into 1,044 centrifuges at the Fordow underground facility, where enrichment was banned in the nuclear agreement, which only allowed scientific research at the site and testing only without gas injections.
The U.S. State Department called the move "a big step in the wrong direction" and accused Tehran of "nuclear extortion," while French President Emmanuel Macron described Iran's decision as "grave."
"Maximum pressure" on Iran would continue to be exerted until it abandons its "destabilizing behavior, including proliferation-sensitive work," a U.S. spokesperson added.
Iranian Foreign Minister Mohammad Javad Zarif said his country was responding to U.S. "economic terrorism & blackmail."
Tehran has gradually reduced some of its commitments under the 2015 nuclear deal since President Donald Trump withdrew the United States from the accord in May 2018.
Meanwhile, Washington has reimposed and expanded punishing sanctions as part of a stated campaign of "maximum pressure" against Iran.
Iranian officials complain that the remaining parties to the deal have failed to mitigate the effects of the U.S. sanctions.
Rohani insisted that all of the steps his country had taken to reduce its commitments to the nuclear agreement were "reversible."
Tehran will uphold all of its commitments under the accord when the remaining signatories -- Britain, France, Germany, Russia, and China -- do the same, the Iranian president said.
Russian Foreign Minister Sergei Lavrov called on Iran to fulfill the terms of the accord, but said Moscow understood why Tehran was cutting back on its commitments.
"They are demanding that Iran fulfill everything without exception, giving [the country] nothing in return," Lavrov told reporters.
Atomic Energy Organization spokesman Kamalvandi said the centrifuges in Fordow will enrich uranium up to 4.5 percent.
Under the nuclear deal, Iran agreed to only produce low-enriched uranium, which has a 3-4 percent concentration and can be used to produce fuel for nuclear power plants.
Weapons-grade uranium is 90 percent enriched or more.
Trump wants to force Iran to renegotiate the 2015 nuclear accord, arguing that the terms were not tough enough to prevent the country from developing nuclear weapons, agree on curbs to its ballistic-missile program, and end its destabilizing activities in the Middle East.
Iran has denied it supports insurgent activity and says its nuclear program is strictly for civilian energy purposes. Iranian officials have also ruled out any negotiations on the country's missile program.