The Iran nuclear deal is in fresh trouble after the UK and other EU powers triggered a “dispute mechanism” in protest at Tehran’s breaches of the agreement.

The move brings the EU a step closer to reimposing sanctions on Iran if the row cannot be resolved and is brought back to the United Nations security council. Iran’s foreign ministry spokesperson said Tehran would give a “firm and serious” response to the move.

But the triggering of the dispute mechanism also could mark a potential setback in Iran’s efforts to separate Europe from the US, which has been pressuring leaders in western capitals to join in its “maximum pressure” campaign against the Iranian regime.

“It definitely takes the deal into a new phase,” Ellie Geranmayeh, a scholar at the European Council on Foreign Relations, told The Independent. “It’s going to be a chapter that the Europeans are going to own, both the process and the outcome.”

The invoking of the dispute mechanism, by the so-called E3 group, came hours after Boris Johnson said the agreement should be scrapped and replaced with a better “Trump deal”, which the US president would negotiate.

The row has escalated after Iran suspended all limits on its production of enriched uranium, in a response to the assassination of Qassem Soleimani.

It marked a further step back from its commitments under the 2015 Joint Comprehensive Plan of Action (JCPOA), because the uranium can be used to make nuclear weapons as well as reactor fuel.

It is understood that the E3 had been mulling the move since Iran’s first breaches of its commitments last summer, but regarded Tehran’s initial steps as “technical” and reversible contraventions of its obligations. The decision to trigger dispute resolution mechanisms was taken before Christmas, after Iran began research work with new and more sophisticated types of centrifuge, but the step was delayed until the new year in order to keep Russia and China – also signatories to the JCPOA – on board.

Triggering the mechanism is regarded in European capitals as a means to preserve the JCPOA, and not the start of a process leading to an imminent reference to the UN Security Council and a “snap-back” to pre-2015 sanctions.

Under the terms of the agreement, the mechanism envisages a joint commission of senior officials of signatory nations – including Iran – meeting in the coming days to discuss the claims of a breach and the steps needed to reverse it. The mechanism is subject to renewal every 15 days, but this would happen automatically without the need for a further meeting unless one of the signatories signalled a desire to bring down the agreement altogether.

It is hoped in Europe that the process will provide Tehran with a route back towards compliance. But it is recognised that the timescale within which Iran could acquire a bomb – estimated at less than a year prior to the forging of the agreement – is shortening.

Dominic Raab, the foreign secretary – in a statement to MPs – insisted the EU nations wanted to rescue the agreement, prompting criticism that No 10 and the Foreign Office were at odds.

Emily Thornberry, the shadow foreign secretary, told him: “In the space of two or three days the prime minister has gone from signing a joint statement with France and Germany calling for the retention and restoration of the JCPOA, to calling for it to be scrapped and replaced by some mythical Trump deal.”

And Hilary Benn, a senior Labour backbencher, said: “Either the prime minister wants to maintain this deal or he is now advocating for its replacement. He cannot credibly hold both positions. Which one is the policy of the government?”.

Protests in Iran over downing of plane and tensions with the west Show all 23 1 /23 Protests in Iran over downing of plane and tensions with the west Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranian police officers take position while protesters gather in front of Amir Kabir University AP Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranians demonstrate following a tribute for the victims of the Ukraine Boeing 737 crash in front of the Amirkabir University in the capital Tehran EPA Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranian police dispersed students chanting "radical" slogans during a gathering in Tehran to honour the 176 people killed when an airliner was mistakenly shot down AFP via Getty Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University - People hold flowers as tear gas fired by police rises Online videos purported to show that Iranian security forces fired both live ammunition and tear gas to disperse demonstrators protesting against the Islamic Republic's initial denial that it shot down a Ukrainian jetliner AP Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranian police officers take position while protesters gather AP Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University AFP correspondents said hundreds of students had gathered early in the evening to pay respects to those killed in the air disaster ISNA/AFP via Getty Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranian protester prepares to throw a tear gas canister back at police AP Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University A protester confronts an Iranian police officer AP Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University epa08120223 Iranians protest to show their sympathy with victims of Ukraine International Airlines Boeing 737-800 in front of the Amir Kabir University in Tehran, Iran, 11 January 2020. Media reported that hundreds of Iranians protests in Tehran in solidarity with victims of the Ukraine plane as Iranian military released a statement claiming that Ukraine International Airlines flight PS752 was shot down due to human error. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranian police officers take position while protesters gathe AP Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University Iranians light candles for victims EPA Protests in Iran over downing of plane and tensions with the west Anti-government protest at Amirkabir University epa08120526 Iranians protest to show their sympathy to victims of Ukraine International Airlines Boeing 737-800 in front of the Amir Kabir University in Tehran, Iran, 11 January 2020. The Iranian military released a statement on 11 January 2020 that Ukraine International Airlines flight PS752 was shot down due to 'human error.' The passemger jet en route from Tehran to Kiev crashed minutes after takeoff on 08 January 2020, all all 167 passengers and nine crew members aboard were killed. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran People burn British and Israeli flags during a protest in front of the British embassy, in Tehran. Hundreds of Iranian hardliners gathered for a protest against Britain, a day after the UK ambassador to Iran Robert Macaire was detained after attending a a vigil for the victims of Ukraine passenger jet EPA Protests in Iran over downing of plane and tensions with the west British embassy protestBritish embassy protest in Tehran Chanting "Death to Britain", up to 200 protesters rallied outside the mission a day after the brief arrest of British ambassador Rob Macaire AFP via Getty Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran epa08122502 Iranian hardliners shout slogans as they gather in front of the British embassy during an anti-Britain protest, in Tehran, Iran, 12 January 2020. According to reports, hundreds of Iranian hardliners gathered for a protest against Britain, a day after the UK ambassador to Iran Robert Macaire was detained after attending a a vigil for the victims of Ukraine passenger jet. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran Iranian demonstrators hold placards bearing the images of slain military commander Qasem Soleimani and Iran's Supreme Leader Ayatollah Ali Khamenei in front of the British embassy in the capital Tehran on January 12, 2020 following the British ambassador's arrest for allegedly attending an illegal demonstration. - Chanting "Death to Britain", up to 200 protesters rallied outside the mission a day after the brief arrest of British ambassador Rob Macaire at a memorial for those killed when a Ukraine airliner was shot down. (Photo by ATTA KENARE / AFP) (Photo by ATTA KENARE/AFP via Getty Images) ATTA KENARE AFP via Getty Images Protests in Iran over downing of plane and tensions with the west Protesters chant slogans and hold up posters of Gen. Qassem Soleimani while burning representations of British and Israeli flags, during a demonstration in front of the British Embassy in Tehran, Iran, Sunday, Jan. 12, 2020. A candlelight ceremony late Saturday in Tehran turned into a protest, with hundreds of people chanting against the country's leaders â€” including Supreme Leader Ayatollah Ali Khamenei â€” and police dispersing them with tear gas. Police briefly detained the British ambassador to Iran, Rob Macaire, who said he went to the Saturday vigil without knowing it would turn into a protest. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran epa08122741 Iranian hardliners gather in front of the British embassy during an anti-Britain protest, in Tehran, Iran, 12 January 2020. According to reports, hundreds of Iranian hardliners gathered for a protest against Britain, a day after the UK ambassador to Iran Robert Macaire was detained after attending a a vigil for the victims of Ukraine passenger jet. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west A hardline protester holds up a placard during a demonstration in front of the British Embassy in Tehran, Iran, Sunday, Jan. 12, 2020. A candlelight ceremony late Saturday in Tehran turned into a protest, with hundreds of people chanting against the country's leaders â€” including Supreme Leader Ayatollah Ali Khamenei â€” and police dispersing them with tear gas. Police briefly detained the British ambassador to Iran, Rob Macaire, who said he went to the Saturday vigil without knowing it would turn into a protest. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran epa08122743 Iranian hardliners gather in front of the British embassy during an anti-Britain protest, in Tehran, Iran, 12 January 2020. According to reports, hundreds of Iranian hardliners gathered for a protest against Britain, a day after the UK ambassador to Iran Robert Macaire was detained after attending a a vigil for the victims of Ukraine passenger jet. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran epa08122745 Iranian hardliners gather in front of the British embassy during an anti-Britain protest, in Tehran, Iran, 12 January 2020. According to reports, hundreds of Iranian hardliners gathered for a protest against Britain, a day after the UK ambassador to Iran Robert Macaire was detained after attending a a vigil for the victims of Ukraine passenger jet. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west British embassy protest in Tehran epa08122786 Iranian hardliners gather in front of the British embassy during an anti-Britain protest, in Tehran, Iran, 12 January 2020. According to reports, hundreds of Iranian hardliners gathered for a protest against Britain, a day after the UK ambassador to Iran Robert Macaire was detained after attending a a vigil for the victims of Ukraine passenger jet. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Protests in Iran over downing of plane and tensions with the west Protesters chant slogans while holding up posters of Gen. Qassem Soleimani during a demonstration in front of the British Embassy in Tehran, Iran, Sunday, Jan. 12, 2020. AP

But Mr Raab said: “He is just wrong. Of course you can want to preserve this deal, but be ambitious if it’s possible, to bring in the US and Tehran into a broader rapprochement dealing.”



Meanwhile, German foreign minister Heiko Maas said the Europeans “could no longer leave the increasing Iranian violations of the nuclear agreement unanswered”.



“Our goal is clear,” he said in a statement. “We want to preserve the agreement and reach a diplomatic solution within its framework. We will tackle this together with all partners to the deal. We call on Iran to participate constructively in the negotiation process that is now beginning.”

The E3 have tried, with Russia and China, to keep the agreement alive ever since Donald Trump pulled the US out in 2018, long before the latest crisis.

But anger has grown in Iran over crippling US sanctions which have caused its oil exports to collapse and the value of its currency to plummet, resulting in soaring inflation.



Iran contends that by largely abiding by US sanctions, European powers have been complicit in the US campaign to pressure the country. But European officials argue they have little control over the private businesses that decline to do commerce with Iran for fear of triggering American reprisals.



The move by the E3 had been long anticipated, especially after Iran’s most recent downgrading of its commitment to the terms of the deal. But experts fear it could trigger a fresh round of escalation between Iran and the west.



“There’s a backdrop of military escalation happening between the US and Iran,” said Ms Geranmayeh. “The Iranians have left open the door for a diplomatic effort. If they feel that the Europeans in addition to the Americans are cornering them and it might encourage them to expand the nuclear programme further.”



In a joint statement, the E3 said: “Iran has continued to break key restrictions set out in the JCPOA. Iran’s actions are inconsistent with the provisions of the nuclear agreement and have increasingly severe and non-reversible proliferation implications.

“We do not accept the argument that Iran is entitled to reduce compliance with the JCPOA.”

They said Iran’s decision on 5 January to suspend the last key commitment on uranium enrichment – the limit on the number of uranium centrifuges – had left them with no choice but to invoke the dispute resolution mechanism.

“We do this in good faith with the overarching objective of preserving the JCPOA and in the sincere hope of finding a way forward to resolve the impasse through constructive diplomatic dialogue, while preserving the agreement and remaining within its framework,” the statement said.

Nevertheless, with Iran unlikely to accept further restrictions – and the US president determined to pursue sanctions – the move could spell the end for the five-year deal.

Earlier, Mr Johnson heaped praise on Mr Trump’s negotiating skills, saying: “Let’s replace it [the JCPOA] with the Trump deal. That’s what we need to see. I think that would be a great way forward – President Trump is a great deal-maker.”

He added: “Let’s work together to replace the JCPOA and get the Trump deal instead, that’s the opportunity.”

Mr Johnson’s official spokesperson later rejected suggestions that the PM’s comments indicated the UK’s support for the existing JCPOA deal was waning.

The PM’s official spokesperson said: “The JCPOA is the only deal that currently exists which prevents Iran from obtaining a nuclear weapon.

“As the PM has said before – including in New York in September – if in the future we can agree a better deal that has the support of the US as well, then that is something we will work towards.”