Speaking after talks with European, Russian and Chinese officials in Vienna, Abbas Araghchi said that what had been agreed was "good progress" but added: "It is still not meeting Iran's expectations."

Referring to Iran's decision to stop abiding by certain limits on nuclear materials under the deal, Araghchi said: "The decision to reduce our commitments has already been made in Iran and we continue on that process unless our expectations are met."

However, he stressed that the final decision would be with his superiors in Tehran.

"I don't think that the progress we made today would be considered enough to stop our process but the decision is not mine," he added.

Araghchi said that the Europeans had confirmed that INSTEX, a mechanism set up to facilitate trade with Iran and avoid US sanctions, was "now operationalised and the first transactions are already processed".

But he added that "for INSTEX to be useful for Iran, Europeans need to buy oil from Iran or to consider credit lines for this mechanism".