Image copyright Crown copyright 2019 Image caption HMS Prince of Wales leaves Rosyth dockyard

Britain's newest aircraft carrier has sailed out of Rosyth dockyard for the first time.

The £3bn HMS Prince of Wales entered the Firth of Forth on Thursday afternoon ahead of extensive sea trials off the north-east of Scotland.

The ship, which is 280m (919ft) long and displaces 65,000 tonnes, is the sister ship of HMS Queen Elizabeth.

The two new aircraft carriers are bigger than anything previously built for the Royal Navy.

Both carriers are longer than the Houses of Parliament and, from keel to the top of the highest mast, taller than London's Nelson's Column. They could fit three football pitches on each massive flight deck.

They have been built to carry up to 36 new F-35 stealth jets, as well as helicopters but in reality they will routinely sail with fewer than half that number.

The navy and the government believe they are a statement of global ambition, but critics claims they will not fit in with the UK's needs and capabilities.

Image copyright Getty Images Image caption The aircraft carrier sits at anchor at the Queensferry Crossing on the Forth

Once out of the dockyard, HMS Prince of Wales will sit at anchor, before putting to sea for trials later in the week.

HMS Prince of Wales, which will be based in Portsmouth, was assembled at Rosyth from 52 blocks built by six shipyards around the UK, with construction beginning in 2011.

The UK government minister for defence procurement, Anne-Marie Trevelyan, said the new carriers gave Britain a "world-leading capability".

She said the new aircraft carrier was "effectively a floating airfield" that could deliver a credible fighting force anywhere in the world as well as supporting diplomatic and humanitarian operations.

Ms Trevelyan said that, once they were fully operational, one of the carriers would be in a state of readiness at all times.

HMS Prince Of Wales

Cost: £3bn

Flight deck length 280m (919ft)

Weight: 65,000 tonnes

Range: 10,000 nautical miles

Crew: 700

Capability: Able to carry 36 F35B jets and four helicopters

Ms Trevelyan added: "Prince of Wales' departure from Rosyth is a landmark moment for the carrier programme. As the ship takes the next step to becoming fully operational, she carries with her the story of Britain's maritime might.

"This tremendous achievement is a testament to the talent of British industry and I look forward to the moment we can welcome her into the Royal Navy family."

HMS Prince of Wales' Captain Darren Houston said: "I am immensely proud of the professionalism and determination that my ship's company have shown in preparing themselves and their ship for this historic day."

Simon Lister, managing director of the Aircraft Carrier Alliance, which built both carriers, said the HMS Prince of Wales had been constructed for 18% less than HMS Queen Elizabeth because lessons had been learned from the first assembly.

'Best of British industry'

Mr Lister said: "The Aircraft Carrier Alliance has bought together the very best of British industry, and it is thanks to their hard work, skill and determination that we have reached this important stage in the programme.

"By working together as one team, we are now able, on schedule, to start testing this magnificent ship in preparation for handing her over to the Royal Navy."

HMS Prince of Wales is expected to commission into the Royal Navy next year. It should be fully ready for frontline duties from 2023.

Meanwhile, HMS Queen Elizabeth is currently in America preparing to undergo further flight trials.

It will deploy operationally for the first time in 2021.