Britain's Foreign Office said in a statement that the "investigations conducted around the Grace 1 are a matter for the government of Gibraltar" and that it couldn't comment further.
In the meantime, Britain continues plans to deploy a Europe-led "maritime protection mission" to safeguard shipping in the area after Iran's Revolutionary Guard seized the Stena Impero in the Strait of Hormuz on Friday.
The audio shows that a British frigate was too far away from the targeted tanker to keep it from being diverted into an Iranian port despite U.K. efforts to keep it from being boarded.