HMS Montrose, a British frigate, has been tasked to sail alongside the ships in the strait for protection.
“The Royal Navy has been tasked to accompany British-flagged ships through the Strait of Hormuz, either individually or in groups, should sufficient notice be given of their passage,” a government spokesperson said on Thursday.
“Freedom of navigation is crucial for the global trading system and world economy, and we will do all we can to defend it.”
Tensions have spiked between Iran and Britain since last Friday when Iran’s Revolutionary Guard Corps and Corps seized the British-flagged Stena Impero and its 23 crew members in the world’s most important waterway for oil shipments.
The incident came two weeks after British forces captured an Iranian oil tanker near the British-controlled territory of Gibraltar, accused of violating sanctions on Syria.
The British government had previously advised British-flagged vessels to avoid the Strait of Hormuz where possible and to notify the navy if they must cross it, but had said it would not be able to escort every ship.
Britain has been seeking to put together a European-led maritime protection mission to ensure safe shipping through the Strait of Hormuz after Iran’s seizure of the tanker in what London said was an act of “state piracy”.
The now-former foreign secretary Jeremy Hunt told parliament that the Montrose had escorted 30 merchant vessels through the strait in 17 separate transits as of Monday.
The UK Chamber of Shipping trade association, which previously called for more protection of merchant vessels in the area, welcomed the new policy.
“This move will provide some much-needed safety and reassurance to our shipping community in this uncertain time,” said chief executive Bob Sanguinetti. “We will continue to push for a de-escalation of tensions in the region.”
On Wednesday, Iran’s President Hassan Rouhani hinted at a possible swap deal between London and Tehran for the seized tankers.
“If Britain steps away from the wrong actions in Gibraltar, they will receive an appropriate response from Iran,” Rouhani said during a weekly cabinet meeting.
About a fifth of the world’s oil passes through the Strait of Hormuz and shipping companies are already deploying more unarmed security guards.
The United States, Britain and other nations will be meeting in Florida on Thursday to discuss the passage.
On average, 15-to-30 large British-flagged ships travel in the Gulf every day, with up to three passing through the Strait of Hormuz between Iran and Oman, where a pair of two-mile-wide (3.2km) shipping lanes provide the only routes in and out of the Gulf.