The Royal Navy will accompany British-flagged vessels through the strait of Hormuz to defend freedom of navigation after Iran seized a tanker this month, the Ministry of Defence has said.

“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 British government spokesman said. “Freedom of navigation is crucial for the global trading system and world economy and we will do all we can to defend it.”

It is an interim move before discussions about the development of an international maritime protection force in the Gulf either led by Europe in coordination but separate from the US or jointly with the US. The US is calling a conference on the issue on Thursday.

Jeremy Hunt as foreign secretary had proposed a European maritime force, arguing it was likely to garner more support than a US-led convoy as the US wanted to scrap the Iran nuclear deal and European powers did not.

Differing national approaches to the nuclear deal were seen as likely to colour the terms of engagement for protecting European shipping going through the strait, ministers argued.

It is not yet clear whether Boris Johnson’s new administration will pursue winning favour with Europe, which might irritate the US as it is the dominant naval force in the area.

Some Gulf states are proposing an international maritime conference, to which Iran would be invited, to try to agree on basic principles of maritime protection. The conference would be held in either France or Germany and include countries such as India, China and Japan as well as Gulf shipping states such as Saudi Arabia and the UAE.

Supporters of a conference argue it could either agree at minimum on a collective statement on the sanctity of shipping or establish a contact group to provide early warning and advise of threats to shipping.

The Royal Navy has already issued advice to British-flagged ships to contact it before trying to go through the strait of Hormuz. The Swedish-owned, British-flagged Stena Impero was seized in the strait a week ago in what was seen as a tit-for-tat measure in response to the British capture of the Iranian tanker Grace 1 in Gibraltar.

The UK has been advising British ships not to go through the strait of Hormuz at present but at least two ships – the Cayman Islands-flagged chemical tanker Oriental Freesia and the Bermuda-flagged BW Nantes – appeared to be ready to attempt it. Other tankers looked to be following the Department for Transport’s advice or were waiting for a Royal Navy escort. HMS Montrose is currently in the area and is due to be replaced by HMS Duncan.

Bob Sanguinetti, the chief executive of the UK Chamber of Shipping, said: “Freedom of navigation is a fundamental principle of international maritime law … This move will provide some much needed safety and reassurance to our shipping community in this uncertain time.”

However, there is an urgency for the UK to protect not just individual ships but also an industry under threat. The UK shipping register lost nearly one-third of its tonnage in just four months owing to the threat of Brexit and is expanding eligibility for the flag to include Commonwealth countries and a further 20 countries on top of that.

There are fears that many ships will deregister from the UK if they feel they represent a specific target for the Iranians.