Having strengthened its stockpile of enriched uranium before the resumption of negotiations this month, Washington said Tehran was approaching the point of no return to revive the nuclear agreement.

The United States Envoy for Iran, Robert Mali, stated that Tehran risked having no benefit in reviving the agreement that had been pending since the withdrawal of the United States in 2018.

At the Manama Dialogue Forum in Bahrain, Mali said: "If Iran continues at this pace of progress (in its nuclear programme), there will come a day when it will be impossible, even if we return to the Joint Comprehensive Plan of Action, to recover the gains" of the Agreement.

He added: "Iran's progress is widespread throughout the region... This is what makes time pass faster and makes us all say that time is running out to return to the nuclear agreement. "

This follows the IAEA's announcement that Tehran has re-increased its stockpile of highly enriched uranium, as it prepares to hold talks with world powers in Vienna on November 29.