French diplomats have added their weight to European efforts to convince Iranian authorities of the need to make progress on talks to moderate the country's nuclear programme.
Iran's Foreign Minister Abbas Araghchi was told Europe would reactivate UN sanctions if Tehran does not make progress on a deal by the end of August.
A "snapback" mechanism – which allows for the reimposition of all international sanctions against Iran – could be deployed, said the French Foreign Ministry.
"It could be used In the absence of concrete progress towards a deal on the nuclear programme by the end of the summer," said a French Foreign Ministry spokesperson.
"Pressure is being applied to convince Iran of the urgency of returning to the diplomatic path without delay, in order to reach a robust, verifiable, and durable agreement on Iran's nuclear programme." the spokesperson added.
The state of Iran's nuclear programme has come under intense scrutiny since Israeli and US strikes on Iranian military and nuclear facilities in June.
A clause in Iran's 2015 nuclear agreement says UN sanctions against Tehran can come back if the country fails to comply with the terms of the deal.
European diplomats want to make headway during the summer as the agreement is due to expire in October.
Rounds of negotiations
Since April, Iranian and American officials have held several rounds of negotiations through Omani mediators. On 13 June, Israel launched an attack on Iran. American forces also carried out strikes on Iran.
Since the end of the hostilities on 24 June, both Iran and the US have signalled that they are willing to return to the negotiating able.
However, a sticking point remains. Tehran says it will not renounce its right to the peaceful use of nuclear power.
The American administration is opposed to Iran possessing the means to build a nuclear bomb.
