The state-run IRNA news agency quoted Foreign Minister Mohammad Javad Zarif as making the uranium announcement. IRNA reported that Zarif, answering a reporter’s question whether Iran had broken the limit, said: “Yes.”

“If Europeans do what they have to do, our measures are reversible,” Zarif said, according to IRNA.

The United Nations’ nuclear watchdog, the International Atomic Energy Agency, confirmed on Monday that Iran had broken through the limit.

“We can confirm that IAEA Director General Yukiya Amano has informed the board of governors that the agency verified on July 1 that Iran’s total enriched uranium stockpile exceeded (the deal’s limit),” the agency said in a statement

Breaking the stockpile limit by itself does not radically change the one year experts say Iran would need to have enough material for an atomic bomb, if to choose to pursue one. Iran has long insisted its nuclear programme is for peaceful purposes, despite Western fears about it.

But by coupling an increasing stockpile with higher enrichment, it begins to close that one-year window and hamper any diplomatic efforts at saving the accord.

Under terms of the nuclear deal, Iran agreed to have less than 300 kilograms of uranium enriched to a maximum of 3.67 per cent. Previously, Iran enriched as high as 20 per cent, which is a short technical step away from reaching weapons-grade levels. It also held up to 10,000 kilograms of the higher-enriched uranium.

Zarif was quoted as also saying that the country remained on track to raise its enrichment if Europe did not take any additional steps toward saving the accord.

“The next step is about the 3.67 per cent limitation, which we will implement too,” he warned.