The Ministry of Defence has been told it must develop a better understanding of the future costs of a Carrier Strike capability after a report highlighted concerns over its aircraft and support ships.
Carrier Strike centres around the Royal Navy's two new Queen Elizabeth-class aircraft carriers, HMS Queen Elizabeth and HMS Prince of Wales, and the F35 Lightning jets that fly from their decks.
A report from the National Audit Office (NAO) said the MOD needs to focus on crucial support for the warships.
The NAO said the MOD has only one ship which is able to resupply the carriers with the supplies they need, such as ammunition and food.
It said the MOD had made slow progress developing three new support ships which are crucial to Carrier Strike’s operation.
These will not be available until the late 2020s and there will be an additional cost in keeping the current ship in operation to fill the gap.
The carriers will be equipped with F35 Lightning jets, the MOD intends to buy 138 in a bid to see the aircraft on the carriers for the next 40 years.
So far it has ordered 48 jets and has deferred receipt of seven of the jets to 2025, a year later than planned, because of financial pressures.
The cost of the Lightning project has increased by 15% from £9.1 billion to £10.5 billion because of additional expenditure on system upgrades, integration of UK weapons and sustainment costs.
The NAO report says if the MOD buys fewer aircraft than originally intended this could affect how the carriers can be used.
Carrier Strike is still on target to reach its "initial operating capability" by December 2020 but the NAO warns that it will be without its full level radar system.
The Crowsnest airborne radar system, which forms a crucial part of its defences, is running 18 months behind schedule.
The head of the NAO, Gareth Davies said: "The MOD has made good progress with the big-ticket items needed to deliver Carrier Strike, such as the carriers, the first squadron of jets and the new infrastructure.
"But it must pay much greater attention to the supporting capabilities needed to make full use of Carrier Strike.
"The MOD also needs to get a firmer grip on the future costs of Carrier Strike.
"By failing to understand their full extent, it risks adding to the financial strain on a defence budget that is already unaffordable."
Meg Hillier, chair of the Commons Public Accounts Committee which follows the work of the NAO, said the Navy was in danger of being left with a “hollowed-out” capability unless the issues were addressed.
"The Ministry of Defence has lofty ambitions for the carriers but hasn’t put its money where its mouth is," she said.
"Worryingly, it still doesn’t know the full cost of supporting and operating Carrier Strike."
A MOD spokesman said: "Carrier Strike is a complex challenge, which relies on a mix of capabilities and platforms. We remain committed to investing in this capability, which demonstrates the UK’s global role.
"Despite the disruptions of COVID-19, the Carrier Strike group is on track for its first operational deployment."
Cover image: An F-35B fighter jet on aircraft carrier HMS Queen Elizabeth earlier this month (Picture: Royal Navy).