A British bid to sell submarine-hunting warships to Norway cannot go ahead unless the Royal Navy agrees to take late delivery of one of its own vessels, it has emerged.

Oslo this month set out plans to buy at least five frigates, starting with at least one for delivery by 2029, as it grapples with an increasingly active Russian presence in the Norwegian and Barents seas.

It is thought BAE Systems could be in pole position to supply the vessels, with the UK defence giant currently building a new generation of Type 26 frigates at its Govan shipyard in Glasgow.

However, the company is committed to supplying the first eight to the Royal Navy, with the first batch of four currently under construction.

It is understood that due to the tight Norwegian timelines, BAE would only be able to supply a frigate to Oslo by its 2029 deadline if the Royal Navy agreed to give up one of the early-stage hulls.

The Navy is currently expecting to take delivery of the Type 26 frigates from 2028 to 2035, with the first, HMS Glasgow, currently being outfitted ahead of sea trials planned for 2026.

Also known as the City-class, the warships will be among the most advanced and stealthy vessels of their kind in the world and used for hunting submarines, air defences and general duties.

On Friday, the Ministry of Defence confirmed that discussions were taking place about the matter but stressed that no decisions had been taken.

Providing the ships to Norway, a fellow Nato member, would support the UK’s defence aims while also helping to guarantee work for BAE’s Glasgow shipyard beyond the mid-2030s.

At the same time, the company’s chances of striking a deal with Oslo have improved after a recent US review found that Fincantieri Marinette Marine, which makes the rival Constellation-class frigate, is suffering a three-year delay on existing orders.

However, handing over UK ships to an ally at a time when the Royal Navy surface fleet is already stretched could prove controversial domestically.

If the Navy agreed, industry insiders have speculated BAE would likely divert one of the earlier-stage hulls known as Ship 3 and Ship 4, or HMS Belfast and Birmingham respectively.

An MoD spokesman said: “We are working jointly with BAE Systems on options to support Norway’s future frigate programme and actively support the promotion of the Type 26 Global Combat Ship design to other navies around the world with a similar requirement.”

A BAE spokesman added: “We’re committed to delivering the eight ship Type 26 programme for the Royal Navy and are making good progress with construction underway on the first four vessels.”

Sidharth Kaushal, sea power research fellow the Royal United Services Institute, said the Royal Navy’s surface fleet’s current state was “effectively one of temporary retrenchment, which may start to be alleviated by the delivery of the Type 26s”.

He added: “The fleet is at a historic low in terms of surface escort ships and the Type 26 will be particularly critical to what the Royal Navy does in future.

“They are already looking at a reduced number, down to eight from the original 12 the Navy wanted, so I imagine giving one to an ally would be a difficult sell.”

BAE has secured contracts worth £7.9bn overall from the Ministry of Defence to build the Type 26 frigates, which will be among the most advanced and stealthy warships in the world.

They are designed for anti-submarine warfare as well as air defence and general purpose operations, replacing some of the functions of the existing fleet of Type 23 frigates.

When outfitted by the Royal Navy, they will be equipped with a medium-calibre gun, Sea Ceptor missiles, a towed sonar array and a helipad capable of accommodating heavy-lift Chinook helicopters.

They will also boast Thunderbird Two-style “mission bays” capable of transporting boats, drones, special forces equipment, disaster relief supplies or up to eight container-sized “pods”.

Both the Ministry of Defence and BAE have previously expressed hopes that the Govan shipyard could also build Type 26s for export, although so far deals to sell the ships to Australia and Canada have seen those countries opt to build them domestically.