Sir Keir Starmer and Emmanuel Macron will co-host a summit in Paris this week to continue efforts to reopen the Strait of Hormuz.
The prime minister has made efforts to reopen the Strait a priority after its closure amid the US-Iran war prompted oil prices around the globe to soar.
International leaders will gather on Friday in an effort to come up with a plan to ensure the vital trading route can remain open to shipping amid Donald Trump’s blockade.
A Downing Street spokesperson said: “The summit will advance work towards a coordinated, independent, multinational plan to safeguard international shipping once the conflict ends.”
Sir Keir told MPs on Monday the UK-French initiative would involve “military planning to provide assurance to shipping” as well as diplomatic efforts.
Mr Macron has previously said the countries participating in the initiative would work on a “strictly defensive mission, separate from the warring parties to the conflict”, which “is intended to be deployed as soon as circumstances permit”.
He said the summit would bring together countries “prepared to contribute alongside us” to the “peaceful multinational mission”.
The route was initially blockaded by Iran in response to US-Israeli attacks on Tehran, a move which has sparked global instability and prompted concerns about the cost of living in the UK.
After ceasefire talks between Tehran and Washington broke down over the weekend, Trump said the US military will now block Iranian vessels and any ships that have already paid Iran tolls coming through the Strait.
Nato allies, including Britain and France, have already said they would not be drawn into the conflict by taking part in Mr Trump’s blockade, stressing instead the need to reopen the waterway.
The war has driven up energy prices, caused stock market turmoil and exposed deep divisions between the US and its traditional European allies.
Oil prices retreated back below 100 US dollars a barrel in Tuesday morning trading on hopes that US-Iran negotiations may be revived and that an agreement could be reached over the crucial Strait of Hormuz.
Meanwhile, in Westminster, the new Middle East Response Committee has been established to deal with the fallout from the Iran conflict and to deal with the domestic and international impacts of the war.
No 10 insiders compared the new panel to the committees set up under Tory prime ministers to deal with Brexit preparations and the Covid-19 pandemic.
A source said the “new central structure” would focus on “medium-term scenario planning to respond to developments in the region over the coming weeks and months”.
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