ShareSaveBen HattonShareSaveBBCThe UK has agreed to a US request to use British military bases for "defensive" strikes on Iranian missile sites, Sir Keir Starmer has said.
But the prime minister said it "remains the case" that the UK is not involved in strikes on Iran and will "not join offensive action now".
Sir Keir said the basis of the decision was the "collective self-defence" of allies and protecting British lives, accusing Iran of pursuing a "scorched-earth strategy".
The US will use the bases for the "specific and limited defensive purpose" of destroying Iran's missiles "at source", he added.
He said the move was in accordance with international law, and the government would publish a summary of its legal advice.
Sir Keir previously said UK aircraft were "in the sky" in the Middle East as part of a defensive operation to protect its allies and citizens in the region.
In a statement posted on social media on Sunday evening, Sir Keir said British aircraft had successfully intercepted Iranian strikes, but added: "Our partners in the Gulf have asked us to do more to defend them and it's my duty to protect British lives."
He added: "The only way to stop the threat is to destroy the missiles at source, in their storage depots, or the launchers which are used to fire the missiles.
"The United States has requested permission to use British bases for that specific and limited defensive purpose.
"We have taken the decision to accept this request to prevent Iran firing missiles across the region, killing innocent civilians, putting British lives at risk, and hitting countries that have not been involved."
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