Sanctions on Iran related to an international nuclear treaty will be written into UK law to prevent them from being lifted next month.
Britain, along with France and Germany, said the sanctions would remain in place due to continued non-compliance with the Joint Comprehensive Plan of Action (JCPoA) with Tehran.
The sanctions due to be kept by the three European countries, known as E3, ban Iran from developing ballistic missiles capable of delivering nuclear weapons and bar anyone from buying, selling or transferring drones and missiles to and from Iran.
The measures had been due to expire on October 18 as part of the multilateral nuclear deal struck eight years ago.
The accord was negotiated in 2015 between Iran, the US, the UK, France, Germany, China, Russia and the European Union to prevent Tehran from developing atomic weapons.
A spokesman for the Foreign, Commonwealth and Development Office said: “Iran continues to breach its commitments under the JCPoA and advance its nuclear programme beyond all credible civilian justification.
“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.”
Under the terms of the accord, Tehran agreed to limit enrichment of uranium to levels necessary for nuclear power in exchange for the lifting of economic sanctions.
In 2018, then-president Donald Trump unilaterally pulled the United States out of the pact.
Iran then began breaking the terms a year later and is now enriching uranium to nearly weapons-grade levels, according to a report by the United Nations’ nuclear watchdog.
The Middle East nation has violated the sanctions by developing and testing ballistic missiles and sending drones to Russia for its war on Ukraine.
FCDO officials said the decision to write the sanctions into UK law do not violate the JCPoA and was “fully consistent with the procedures defined within” the treaty.
London said Iran has consistently breached its obligations under the JCPoA, with the regime’s enriched uranium stockpiles 18 times the limit set out in the agreement.
The UK Government said that in March 2022 and again last month Britain and its partners offered Iran viable deals that would have defused the nuclear issue but said Tehran turned it down on both occasions.
The sanctions will remain in place until Tehran “is fully compliant” with the deal, the E3 said.