Sweeping UN economic and military sanctions have been reimposed on Iran – 10 years after they were lifted in a landmark international deal over its nuclear programme.

The new measures took effect as the three European partners to the deal – the UK, France and Germany – activated the so-called “snapback” mechanism, accusing Iran of “continued nuclear escalation” and lack of co-operation.

Iran suspended inspections of its nuclear facilities – a legal obligation under the terms of the 2015 deal – after Israel and the US bombed several of its nuclear sites and military bases in June.

Its President Masoud Pezeshkian insisted last week that the country had no intention of developing nuclear weapons.

The reintroduction of sanctions – which Pezeshkian described as “unfair, unjust, and illegal” – is the latest blow to a deal that was heralded as a turning point in Western relations with the long-ostracised Islamist nation when it was first struck.

The Joint Comprehensive Plan of Action (JCPOA) places limits on Iran’s nuclear installations, its stockpiles of enriched uranium, and the amount of research and development it can undertake.

It aims to allow Iran to develop its nuclear power infrastructure without straying into making nuclear weaponry.

Iran stepped up its banned nuclear activity after Donald Trump pulled the US out of the agreement during his first term as president in 2016.

He has persistently criticised the deal, negotiated under his predecessor Barack Obama, as flawed, vowing to negotiate better terms.

The US and Israeli bombing of nuclear facilities in June was intended to reverse some of Iran’s nuclear progress, as well as punish it for arming regional proxies that have repeatedly attacked Israel.

While Trump said these had caused “monumental damage”, others cast doubt on the extent to which they had hindered Iran’s nuclear programme.

Iran said the strikes “fundamentally changed the situation” and rendered international support for the nuclear deal “obsolete”.

European allies that remain party to the deal still hope negotiations will yield a cooling of tensions.

“We urge Iran to refrain from any escalatory action,” they said in a joint statement, adding: “The reimposition of UN sanctions is not the end of diplomacy.”

Talks between the three countries and Iran on the sidelines of the UN General Assembly earlier this week failed to produce a deal which would have delayed the sanctions being reimposed.

The foreign ministers of the so-called E3 said they had “no choice” but to trigger the snapback procedure, as Iran had “repeatedly breached” its commitments.

They cited Iran’s failure to “take the necessary actions to address our concerns, nor to meet our asks on extension, despite extensive dialogue”.

Specifically, they mentioned Tehran’s refusal to co-operate with the UN nuclear watchdog, the International Atomic Energy Agency (IAEA).

“Iran has not authorised IAEA inspectors to regain access to Iran’s nuclear sites, nor has it produced and transmitted to the IAEA a report accounting for its stockpile of high-enriched uranium,” the statement read.

The suspension of IAEA inspections began following the US/Israeli bombings, but the agency confirmed on Friday that they had resumed.

In a statement on Sunday, Iran said it did not recognise the “illegal” and “unjustifiable” sanctions.

Its foreign ministry warned that “any action aimed at undermining the rights and interests of its people will face a firm and appropriate response”.

Pezeshkian has softened earlier threats of Iran quitting the Non-Proliferation Treaty altogether – but has warned that a return of sanctions would put negotiations in jeopardy.

He told reporters on Friday that Tehran would need reassurances that its nuclear facilities would not be attacked by Israel in order to normalise its nuclear enrichment programme.

He also rejected a US demand to hand over all of Iran’s stockpile of enriched uranium in return for a three-month exemption from sanctions, saying: “Why would we put ourselves in such a trap and have a noose around our neck each month?”

Western powers and the IAEA say they are not convinced by Iran’s insistence that its nuclear programme has purely peaceful purposes.

The government will underwrite a £1.5bn loan guarantee to Jaguar Land Rover (JLR) in a bid to support its suppliers as a cyber-attack continues to halt production at the car maker.

Business Secretary Peter Kyle said the loan, from a commercial bank, would protect jobs in the West Midlands, Merseyside and across the UK.

The manufacturer has been forced to suspend production for weeks after being targeted by hackers at the end of August.

There have been growing concerns some suppliers, mostly small businesses, could go bust due to the prolonged shutdown.

About 30,000 people are directly employed at the company’s UK plants with about 100,000 working for firms in the supply chain. Some of these firms supply parts exclusively to JLR, while others sell components to other carmakers as well.

It is believed to be the first time that a company has received government help as a result of a cyber-attack.

It is hoped the loan will give suppliers some certainty as the shutdown continues, with production not expected to resume at JLR’s UK facilities until 1 October at the earliest.

The government will underwrite the loan through the Export Development Guarantee (EDG), a financial support mechanism aimed at helping UK companies who sell overseas.

The loan will be paid back by JLR over five years, in an effort to boost the firm’s cash reserves as it makes a “backlog of payments” to its suppliers.

No cars have been built this month, and the company has stopped placing orders with its 700 suppliers.

A parliamentary committee said some small suppliers had told them they had, at most, one week left before they ran out of cash.

The halt in operations is thought to be costing JLR itself at least £50m per week.

The manufacturer, owned by India’s Tata Motors, typically builds about 1,000 cars a day at its three factories in Solihull and Wolverhampton in the West Midlands, and Halewood in Merseyside.

Kyle said the loan guarantee would help protect jobs in the West Midlands, Merseyside and elsewhere in the JLR supply chain.

“We are offering a £1.5bn credit facility to JLR with the explicit intention that that is to support the supply chain into JLR as well,” he said.

“This is a big moment: this will offer an enormous resource for JLR and the supply chain to get through the immediate challenges that they face.“

Chancellor Rachel Reeves said: “Today we are protecting thousands of those jobs with up to £1.5bn in additional private finance, helping them support their supply chain and protect a vital part of the British car industry.”

Shadow business secretary Andrew Griffith welcomed the government’s support but said it “took too long to get there” and called on Labour to form a cyber reinsurance scheme to protect British businesses from state-backed actors.

Liberal Democrat business spokesperson Sarah Olney also praised the move but said the government had been “too slow to act”, adding it should also be prepared to provide a furlough scheme for affected workers if required.

Union Unite, representing thousands at JLR and in the supply chain, described the government support as an “important first step”.

“The money provided must now be used to ensure job guarantees and to also protect skills and pay in JLR and its supply chain,” said general secretary Sharon Graham.

JLR was hit by a cyber-attack on 31 August. A group calling itself Scattered Lapsus$ Hunters has claimed responsibility for the hack.

It was also behind a number of high-profile attacks on retailers earlier this year, including Marks & Spencer and Co-op.

JLR workers have been told to stay home since 1 September, with no firm return date provided.

A JLR spokesperson said: “Our teams continue to work around the clock alongside cybersecurity specialists, the NCSC and law enforcement to ensure we restart in a safe and secure manner.

“The foundational work of our recovery programme is firmly under way, and we will continue to provide regular updates to our colleagues, retailers and suppliers.”