The Royal Navy would struggle “to remain credible as a first-class sea power” without the capability of its new aircraft carrier to fly fighter jets, according to the commanding officer of HMS Queen Elizabeth.

Speaking aboard the 65,000-tonne carrier at Portsmouth Naval Base, Captain Jerry Kyd said the capability provided by the giant warship, and its sister ship HMS Prince of Wales which is still being fitted out, brought the Royal Navy into the “top league”.

But he conceded that the navy was only a “medium-sized” force in terms of “mass” of assets.

He said: “This capability genuinely will probably mean we are a country with a medium-sized sea power again. This is a strategic output at the top-end scale.

“If you look around the world and note how many nations have a generation five aircraft carrier tailored and built keel-up for that aircraft with the Type-45 and latest Astute class submarines with a modern commando force to boot, I think we should recognise that puts us back in the top league.

“Without these two ships I think we would be struggling to remain credible as a first-class sea power.

“Tier one in class of capability, in terms of mass we remain a medium-sized navy, in terms of standards and capability, only the US would have more.”

Commodore Andrew Betton, commander of the UK Carrier Strike Group, added: “This is a very important step towards the future of the Royal Navy, that modern maritime task group.

“This is the first small-scale iteration of that and frankly everyone wants to be a part of it and if you’re in Royal Navy uniform why wouldn’t you want to be.”