France, Germany, Britain and the European Union say they are "extremely concerned" about Iran's renewed uranium enrichment activities and what they call "regrettable acceleration of Iran's disengagement" from commitments it made under the 2015 agreement regarding the country's nuclear program.
In a joint statement released Monday, the foreign ministers urged Iran to reverse all of the measures it has taken that go against those imposed in the Joint Comprehensive Plan of Action, which limited Iran's nuclear activity in exchange for sanctions relief.
Iran has restarted enrichment at its Fordow facility, exceeded limits on enrichment levels and the amount of enriched material it is allowed to stockpile, while also announcing work on developing more advanced centrifuges. Iranian President Hassan Rouhani said the steps are reversible if the other signatories to the agreement help Iran work around U.S. sanctions.
In their statement, France, Germany Britain and the EU said their side has "fully upheld" their commitments under the agreement, including lifting the sanctions they had imposed over concerns Iran was working to develop nuclear weapons. Iran says its nuclear program is only for peaceful purposes.
"It is now critical that Iran upholds its JCPOA commitments and works with all JCPOA participants to de-escalate tensions," the statement said.
Iranian Foreign Minister Mohammad Javad Zarif rejected the ministers' characterization of compliance with the agreement.
"'Fully upheld commitments under JCPOA' YOU? Really?" he wrote Tuesday on Twitter. "Just show ONE that you've upheld in the last 18 months."
The deal originally also included China, Russia and the United States. U.S. President Donald Trump withdrew from the agreement last year.
Also Monday, the U.N.'s nuclear monitor said uranium particles have been detected at an undeclared nuclear site in Iran.
In a confidential report obtained by news agencies, the International Atomic Energy Agency (IAEA) confirmed that manmade uranium particles had been discovered, without revealing the location of the undeclared site.
The report also confirmed that Iran is enriching uranium at its underground Fordow facility — a site where, under the 2015 nuclear deal with world powers, it had agreed not to carry out any enrichment or enrichment-related research.
Over the weekend, Iran began pouring concrete for a second nuclear reactor at its Bushehr power plant, which is monitored by the IAEA.
Iran has said it intends to enrich uranium to 4.5%, slightly above the 3.67% limit allowed under 2015 deal. Enriching to 4.5% is far below the level needed to make a nuclear weapon.