The Strait of Hormuz must be reopened with “unconditional and unrestricted” access for shipping, Sir Keir Starmer said as a US-Iran deal appeared to be drawing closer.
US President Donald Trump has said a deal with Iran, which would including opening the strait, a vital oil and gas shipping route, has been “largely negotiated”.
Mr Trump said “final aspects of the deal” are currently being discussed.
The Prime Minister said the UK would work with allies to “seize this moment” to help achieve a long-term solution in the Middle East.
Sir Keir said: “I welcome the progress towards an agreement between the US and Iran.
“We need to see an agreement that brings the conflict to an end and reopens the Strait of Hormuz, with unconditional and unrestricted freedom of navigation.
“It’s vital that Iran must never be allowed to develop a nuclear weapon.
“My Government will continue to do everything we can to protect British people from the impact of this conflict.
“We will work with our international partners to seize this moment and achieve a long-term diplomatic settlement.”
The UK has already announced Royal Navy destroyer HMS Dragon has been sent to the Middle East to prepare for a possible international mission to safeguard shipping in the strait if a peace deal is put in place.
The UK and France have been leading efforts to pull together an international alliance willing to provide reassurance and assist with mine clearance once the hostilities cease.Armed forces minister Al Carns visited RFA Lyme Bay in Gibraltar, a support vessel which can act as a mothership for minehunting drones which could be sent to the Gulf.
But Chief Secretary to the Prime Minister Darren Jones played down the prospect of an imminent peacekeeping mission.
He told Sunday Morning With Trevor Phillips on Sky News: “I’m not sure that that’s on the table right now.
“We have long-standing defence partnerships with countries in the region, anyway, as well as British military bases there, which we’ve talked a lot about in the last few weeks, as this conflict has flared up.
“But I think what is really the question here is how we get the Strait of Hormuz open, how the Americans and others can help to clear mines that may have been laid in the Strait of Hormuz, so that commercial shipping companies have the confidence again to be able to travel through it.”
The strait has been effectively closed to most shipping by Iran since the US-Israeli bombing campaign began at the end of February.
The closure of the strait, which normally carries around 20% of global oil and gas shipping, has driven up prices around the world.
In a post on his Truth Social platform Mr Trump said: “Final aspects and details of the deal are currently being discussed, and will be announced shortly.
“In addition to many other elements of the agreement, the Strait of Hormuz will be opened.”
