France, May 26 -- Hundreds of British sailors are preparing aboard the RFA Lyme Bay off Gibraltar - the UK territory on the southern tip of the Iberian peninsula - for a possible deployment to the Gulf, where the closure of the Strait of Hormuz has disrupted shipping and pushed up the cost of fuel, fertiliser and food.

The mission remains contingent on diplomacy: British officials say any operation to secure the strait would begin only after hostilities have ended and an agreement is in place.

The Royal Fleet Auxiliary vessel is being loaded with ammunition and sonar-equipped mine-hunting sea drones before linking up with the UK destroyer HMS Dragon and allied ships for air support. The force would then travel through the Suez Canal tow...