President Hassan Rouhani reiterated Tehran’s threat to increase the uranium enrichment above the 3.67 per cent purity level agreed under the accord to “what amount we feel like” and revive its Arak heavy-water reactor.

He said this could happen after a July 7 deadline he set to take measures to relieve the economic pressure on Iran.

Yet Mr Rouhani also said Iran would reduce its enriched uranium stockpile if the signatories delivered on their economic pledges.

The White House, in the meantime, said that there was “little doubt” that Tehran had violated its nuclear accord even before it existed.

And Mohammad Javad Zarif summed up Iran’s frustration in a word. “Seriously?” he said on his Twitter account.