According to AP, the International Atomic Energy Agency reported on Monday that its inspectors verified the installation of new centrifuges. The agency said all had been "prepared for testing", but none yet tested at the time of the Sept. 7-8 inspection.
Iran had already announced the move, namely exceeding the deal’s limits on research and development, as the third step in a strategy it began to implement in May.
It has been reducing its nuclear commitments under the 2015 nuclear deal in phases to pressure European signatories to find a way to maintain oil shipments and ease the toll of US sanctions on the Iranian economy.
Tehran has already pushed past limits in the agreement, called the Joint Comprehensive Plan of Action, on nuclear enrichment purity and stockpiles of enriched uranium in response to US sanctions imposed since Washington withdrew from the deal last year.
Less than 24 hours after Iran said it was starting up advanced centrifuges that enrich uranium at a faster rate, Cornel Feruta—who took over as IAEA chief in an acting capacity after the death of his boss Yukiya Amano in July—visited Tehran to hold talks with Iranian officials.
After his return, Feruta told reporters in Vienna that the Sunday's meetings had gone well, "covering a full range of issues in our cooperation and I was pleased with the tone and the input we received in those conversations", AP reported.
Asked what the new centrifuges could mean to enhance Iran's ability to enrich uranium, the official said "output is not a simple matter", but also it was "not for the agency to judge what these actions will bring".
"We have made it very clear that the role of the agency is to report the facts to members of the JCPOA and also the board," he added.
'Time Is of the Essence'
Speaking at a regular session of the IAEA's 35-nation Board of Governors in Vienna on Monday, Feruta said Iran needs to cooperate with the agency "fully" and "in a timely fashion", the IAEA website reported.
"It is important to advance our interactions and, therefore, I also stressed the need for Iran to respond promptly to agency questions related to the completeness of Iran's safeguards declarations," he was quoted as saying by the IAEA website.
"The agency will continue its efforts and will remain actively engaged. Time is of the essence."
Iran’s Foreign Minister Mohammad Javad Zarif told Feruta that Iran's decision to downgrade its commitments are allowed under Paragraph 36 of the nuclear accord, which spells out the dispute resolution mechanism, ISNA reported.
Zarif also underscored the need for IAEA to respect professional principles, maintain confidentiality and carry out its duties impartially.
According to a press release on the IAEA website, Feruta stressed that IAEA's safeguards activities are conducted in an impartial, independent and objective manner, and in accordance with standard safeguards practices.
'One-Way Street'
Ali Akbar Salehi, the head of the Atomic Energy Organization of Iran, also defended Iran's recent nuclear steps, saying that the nuclear deal has become a "one-way street".
"The European Union was supposed to fill the void created by the US exit, but they failed to act on their promises," Salehi told reporters alongside Feruta in Tehran, ISNA reported.
"JCPOA was not supposed to be a one-way street. If it is going to be one way, the Islamic Republic of Iran will definitely make the right decisions at the right time like it has done with these three steps," Salehi said.
The Russian Foreign Ministry said in a statement on Monday that Iran's restart of its centrifugal research and development works does not pose any threat.
"There is no risk of reorienting Iranian research to undeclared usage. Iran fully observes the Non-Proliferation Treaty, follows the comprehensive safeguards agreement with the IAEA, implements the Additional Protocol," the ministry was quoted as saying by Sputnik.
It added that Iran initiated the third round of steps because of Washington's policies, while urging all parties to the deal to show wisdom and help preserve it.
On the same day, German Foreign Ministry Spokesman Rainer Breul called Iran's centrifuge plans "a step in the wrong direction" and said Berlin supports France's efforts to resume talks and de-escalate the situation.
"We call on Iran to meet its commitments under the JCPOA and to return to them," Breul said.
Iran says its measures are reversible, if European signatories to the accord hold up their end of the deal.
In a separate development, Israeli Prime Minister Benjamin Netanyahu claimed on Monday that Tehran had been developing nuclear weapons at a secret site in Abadeh in Iran but had destroyed the facility after learning it had been exposed.
Zarif rejected the claim, saying that Netanyahu was seeking a pretext for war.
"The possessor of real nukes cries wolf," the senior diplomat said in a tweet, a reference to Israel's own nuclear arsenal.