Sir Keir Starmer called on Iran to “return to the negotiation table” after the United States bombed the country's nuclear site overnight.
The British prime minister said in a statement that stability in the region was a priority, describing Iran's nuclear program as a “serious threat to international security.”
The BBC learned that Britain had not participated in the strike on Iranian nuclear facilities in the United States and the Prime Minister was informed of them in advance.
“Iran will never be able to develop nuclear weapons and the United States has taken action to mitigate the threat,” Starmer added.
Iran has repeatedly stated that its nuclear ambitions are peaceful.
•Follow the latest information: US bombs in three nuclear sites in Iran
• Our strike on our nuclear facilities on Iran
The United States said it had already striked three Iranian nuclear facilities: Natanz, Isfahan and Fudo took a strike on Saturday night.
Then a new Israeli operation against Iran was started overnight until June 13. Israel said its target is military sites including nuclear facilities.
Iran launched a retaliatory strike – the two countries have continued to exchange fires since.
President Donald Trump initially declined to say whether the United States would be involved, and the White House said Friday that it would make a decision “within the next two weeks.”
In a television speech after the strike, the president said the operation was a “spectacular military success” and added that if Iran does not achieve peace quickly, it would face “larger” attacks.
Iran's ambassador to the UK, Seyed Ali Mousavi told BBC's Laura Kuenssberg that Iran is considering the “quantity and quality” of its response to retaliation.
According to the latest update from the United Nations International Atomic Energy Agency (IAEA), on-site radiation has not yet increased.
Iranian Foreign Minister Abbas Araghchi called the U.S. strike “outrageous” and said they would have “eternal consequences.”
He added: “Every member of the United Nations must be shocked by this extremely dangerous, illegal and criminal act.”
UN Secretary-General António Guterres said the overnight strike was a “dangerous escalation.”
“Through nuclear sites targeting Iran, the United States has taken decisive actions to protest global terror and directly threaten the British regime,” Conservative leader Kemi Badenoch said in a response to the U.S. action overnight.
Starmer had previously promoted further negotiations to mitigate the conflict.
“The risk of escalation in the region is obvious,” he said at the time.
Foreign Secretary David Lammy traveled to Washington last week to meet with Secretary of State Marco Rubio and U.S. Special Envoy Steve Witkoff.
After the meeting, the Foreign Secretary said: “We discussed how a deal can avoid deepening conflict. Now, there is a window in the next two weeks to achieve a diplomatic solution.”
He formed part of the European contingent that he met with Iranian officials on Friday.
“Through nuclear sites targeting Iran, the United States has taken decisive action to protest global terror and directly threaten the British regime,” said conservative leader Kemi Badenoch.
Foreign, Commonwealth and Development Office (FCDO) has recommended all trips to Israel and the occupied Palestinian territory and Iran.
