Iran's atomic agency chief hit out Sunday at European powers, saying their broken promises gave the Islamic republic little choice but to scale back its commitments under a nuclear deal.

Ali Akbar Salehi was speaking to reporters alongside Cornel Feruta, the acting head of the International Atomic Energy Agency who was on a one-day visit to Tehran.

The IAEA official's visit comes a day after Iran said it was firing up advanced centrifuges that enrich uranium at a faster rate -- the latest blow to the landmark 2015 nuclear deal.

It was the third step in a strategy Iran implemented in May, reducing its nuclear commitments in a bid to force the deal's remaining parties to deliver on promises of relief from crippling US sanctions.

Britain, France and Germany have been trying to save the nuclear deal, which began unravelling last year when US President Donald Trump withdrew from it and began reimposing the punitive measures against Iran.

"The European Union was supposed to be the replacement of the US but, unfortunately, they failed to act on their promises," Salehi said in comments aired on state television.

"We heard the EU spokesperson say they would be committed to the JCPOA as long as Iran is," he said, referring to the deal by its formal name, the Joint Comprehensive Plan of Action.

"I am wondering. Are they committed to non-adherence? Are they committed to breaking promises? Unfortunately, the Europeans have done this so far."

The head of Iran's Atomic Energy Organisation said the JCPOA was now just a "one-way street".

"The street was supposed to be two-way. If it's 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," said Salehi.

Feruta, for his part, was cited by state media as saying the IAEA was committed to doing its work in an independent and professional manner.

France, which has been leading the European efforts to rescue the nuclear deal, on Sunday urged Iran to halt its steps away from the accord.

"The channels for dialogue are still open, including today... (but) Iran must give up such actions," said Foreign Minister Jean-Yves Le Drian.

Feruta also held talks on Sunday with Iran's top diplomat Mohammad Javad Zarif and Ali Shamkhani, secretary of Iran's Supreme National Security Council, according to state television.

The IAEA said the Romanian diplomat's visit was part of its "ongoing interactions" with Iran as part of its mission to verify and monitor the country's compliance with 2015 deal.

The crumbling accord was meant to give Iran relief from sanctions in return for curbs on its nuclear program.

Iran has taken a series of retaliatory steps to reduce compliance with the deal since the US withdrawal in May 2018.

On July 1, it said it had increased its stockpile of enriched uranium to beyond the 300-kilogram limit set by the agreement.

A week later, the Islamic republic announced it had exceeded the deal's uranium enrichment limit of 3.67 percent.

On Saturday, Iran's Atomic Energy Organisation said it had taken another step by starting up 20 IR-4 and 20 IR-6 advanced centrifuges.

Under the Joint Comprehensive Plan of Action, Iran was allowed to enrich uranium using only first generation -- or IR-1 -- centrifuges.

Despite the latest move, the agency said Iran would allow the IAEA to continue monitoring its nuclear facilities in accordance with the 2015 agreement.

The IAEA said it had noted Iran's latest move and indicated its inspectors were ready to check its compliance.

"Agency inspectors are on the ground in Iran and they will report any relevant activities to IAEA headquarters in Vienna," spokesman Fredrik Dahl said.

Feruta's visit to Tehran comes a day before the IAEA board of governors convenes for a quarterly meeting in Vienna, at which its mission in Iran will be discussed.

In its latest report on Aug. 30, the watchdog said it was continuing to verify compliance through cameras and on-site inspections.

But in an apparent hint at worries about access, it said "ongoing interactions... require full and timely cooperation by Iran". (AFP)