The UK has jointed with the EU to try to block the impact of Donald Trump's new sanctions against Iran.
Jeremy Hunt, the foreign secretary, signed a joint statement with other EU foreign ministers to ensure European countries doing business with Iran would be protected.
The ministers promised to introduce a "blocking statute" to ban European firms from abiding by the US-imposed sanctions, which were reimposed by Mr Trump on Monday.
The Republican decided to reintroduce the penalties after withdrawing from the 2015 Iran nuclear deal negotiated by his predecessor, Barack Obama.
European foreign ministers said the lifting of sanctions was "essential" to the deal, officially known as the Joint Comprehensive Plan of Action (JCPOA).
Mr Hunt signed the statement along with EU High Representative Federica Mogherini and foreign ministers Jean-Yves Le Drian of France and Heiko Maas of Germany.
The ministers said they "deeply regret" Mr Trump's decision to reimpose sanctions, and aside 11 consecutive reports by International Atomic Energy Agency confirmed that the Iran deal "is working".
They said: "It is a key element of the global nuclear non-proliferation architecture, crucial for the security of Europe, the region, and the entire world. We expect Iran to continue to fully implement all its nuclear commitments under the JCPOA.
"The lifting of nuclear-related sanctions is an essential part of the deal – it aims at having a positive impact not only on trade and economic relations with Iran, but most importantly on the lives of the Iranian people. We are determined to protect European economic operators engaged in legitimate business with Iran.
The EU's Blocking Statue will come into effect on Tuesday and will allow European firms to recover damages for losses incurred a a result of the US sanctions. EU companies will also be banned from complying with Mr Trump's sanctions unless they get permission from the European Commission.
The foreign ministers said the statute would "protect EU companies doing legitimate business with Iran from the impact of US extra-territorial sanctions", the said, adding: "Preserving the nuclear deal with Iran is a matter of respecting international agreements and a matter of international security.
European leaders criticised Mr Trump after he walked away from the Iran deal, which saw Iran agree to drop its pursuit of nuclear weapons in exchange for a lifting of Western-imposed economic sanctions.
Following the announcement in May, the leaders of the UK, France and Germany issued a joint statement.
Theresa May, Emmanuel Macron and Angela Merkel said: "Together, we emphasise our continuing commitment to the JCPOA. This agreement remains important for our shared security.
“We recall that the JCPOA was unanimously endorsed by the UN Security Council in resolution 2231. This resolution remains the binding international legal framework for the resolution of the dispute about the Iranian nuclear programme.
“We urge all sides to remain committed to its full implementation and to act in a spirit of responsibility.”
The Independent has launched its #FinalSay campaign to demand that voters are given a voice on the final Brexit deal.
Sign our petition here
