UN sanctions on Iran that were due to be lifted in October are being extended beyond the deadline set by the Joint Comprehensive Plan of Action, the UK government and the EU announced on Thursday.

The UK, France and Germany are set to transfer UN sanctions on Iran into domestic law, as the regime is breaching commitments under the deal and advancing its nuclear programme “beyond all credible civilian justification”.

The sanctions, which were due to lift on October 18, include curbs on people and businesses involved in Iran’s missile, nuclear and other weapons programmes.

“Iran continues to breach its commitments under the JCPOA and advance its nuclear programme beyond all credible civilian justification,” a representative for the UK Foreign Office said.

“Alongside our French and German partners, we have taken a legitimate and proportionate step in response to Iran’s actions.

“The UK and our partners remain committed to a diplomatic solution but Iran must now take clear steps towards de-escalation.

“We are committed to preventing Iran from developing nuclear weapons.”

Iran's nuclear programme – in pictures

New generation Iranian centrifuges on display for Iran's National Nuclear Energy Day in Tehran, in April 2021. Iranian Presidency Office / Wana

The countries believe Iran’s enriched uranium stockpiles are more than 18 times the JCPOA limit, and it has built and deployed thousands of advanced centrifuges.

Iran has been offered viable deals that would have defused the nuclear issue, but the regime consistently declined, the UK government said.

The UK, France and Germany began the JCPOA’s Dispute Resolution Mechanism in January 2020 in response to Iranian non-compliance to try to find a solution.

The process is supposed to allow 30 days to resolve outstanding issues, but it has now been more than three and a half years and Iran remains out of compliance, the UK government said in a statement.

An EU representative said details of the developments had been passed to the other JCPOA participants and that they would be consulted on how to proceed.

'Transition Day' a far way off for Iran

Keeping the sanctions would reflect western efforts to prevent Iran from developing nuclear weapons and the means to deliver them despite the collapse of the 2015 deal, which then-US president Donald Trump abandoned in 2018.

The JCPOA envisaged a “Transition Day” eight years later, when remaining ballistic missile and nuclear-related sanctions on Iran would be lifted.

The crux of the agreement, which Iran made with Britain, China, France, Germany, Russia and the US, limited the regime’s nuclear programme, making it harder for it to get fissile material for a bomb in return for relief from economic sanctions.

As a result of Mr Trump’s withdrawal from the deal and US President Joe Biden’s failure to revive it, Iran could make the fissile material for one bomb in about 12 days, according to US estimates, down from a year when the accord was in force.

“Our commitment to finding a diplomatic solution remains. This decision does not amount to imposing additional sanctions nor to triggering the snapback mechanism,” the UK, France and Germany said, referring to a mechanism that would immediately restore all UN sanctions against Iran.

“We stand ready to reverse our decision, should Iran fully implement its JCPOA commitments.”

Updated: September 14, 2023, 7:31 PM