Britain, the United States and other nations will meet at a US base to discuss plans to protect ships in the Gulf from Iranian attacks, Sky News reports.
The countries will meet in Florida on Thursday.
The Gulf crisis is the most acute foreign policy challenge facing incoming British Prime Minister Boris Johnson.
The “force generation” meeting will take place at Central Command in Tampa.
It is is part of a US-led push to build a coalition of navies to escort commercial tankers through the Strait of Hormuz and other key waterways in the Middle East as well as to provide increased surveillance, according to two Whitehall sources.
Countries taking part may offer a sense of what warships, surveillance aircraft and personnel they would be able to contribute.
It is not clear how a plan announced by foreign secretary Jeremy Hunt for a European-led maritime protection force will fit with the US initiative, which is called Operation Sentinel.
Mr Hunt told parliament on Monday the European force would be separate to the US coalition but he hoped it would be complementary.
The two Whitehall sources told Sky News they are not sure how viable a bespoke European naval force would be and that the only nation with the capability to lead a coalition of this nature is the United States.
“Nobody here sees how” a European-led maritime force can happen, one source said.
“Unless on Thursday, under a US chair, they negotiate enough capability to form a force and pass it to the European Union to command and coordinate.
“But why would they do that? Perhaps to give US continued diplomatic space to continue with Iran rhetoric?”
It is understood that the aim of tomorrow’s conference is to bring together as many nations as possible to protect shipping lanes through increased maritime awareness and coordination of activity regardless of flag, ownership, or cargo.
European countries, including Britain, had been reluctant to respond to calls by President Donald Trump in recent weeks to join the US-led mission because US policy on Iran is at odds with Europe after Washington withdrew from a 2015 nuclear deal with Tehran last year.
Britain and its European allies still support the nuclear accord and are concerned that siding with the US on a maritime mission in the Gulf would reduce the deal’s chances of survival even further.
At the same time, they agree on the need for increased security for international shipping in the Gulf in the wake of limpet mine attacks on tankers and the seizure by Iran last Friday of a UK-flagged tanker in the Strait of Hormuz.
The thinking behind proposing a European-led force was that it would be easier for European allies to join up as the US would be at arms length.
One Whitehall source, however, said while this is a logical argument there aren’t “any credible offers coming forward” from the Europeans.
Positive noises have reportedly been made by France, Italy and Denmark but they are not the same as committing warships, aircraft and personnel, a second source said.
Germany said it is talking to the UK about its idea for a naval mission in the Gulf but “it is too early today to talk about the form of possible German support or participation”.
For British-linked ships and tankers operating in the Gulf, the need for greater protection is immediate.
The UK government has advised vessels to avoid the Strait of Hormuz since the capture of the Stena Impero tanker and its 23 foreign crew.
But one maritime industry source said there has been no indication as to how long they had to avoid the area or when any kind of official military escort service would be starting.
Shipping companies also have to cope with a significant hike in insurance cover for ships in and around the Straight of Hormuz.
The price for a tanker for seven days’ cover has risen to at least $100,000 (£80,020) for seven days compared with $25,000 (£20,005) about six weeks ago, the source said