UK Prime Minister Keir Starmer insists it was his "duty" to determine which actions in Iran best serve Britain's interests.

"The United Kingdom did not participate in the initial US and Israeli strikes on Iran. That decision was deliberate. We believe the best path for the region and for the world is to reach a negotiated agreement in which Iran agrees to abandon any ambitions to develop nuclear weapons and to cease its destabilising activities in the region.

"This has been the established position of successive British governments. President Trump expressed disagreement with our decision not to take part in the initial strikes, but it is my duty to assess what is in the national interest of the United Kingdom. That is what I did, and I stand by that decision."