The Government is to buy nine maritime patrol aircraft as part of a £3 billion, 10-year partnership with Boeing.

The Ministry of Defence said the P-8A Poseidon planes will be based at RAF Lossiemouth in Moray to help protect the Trident nuclear weapons system and the UK's two new aircraft carriers.

Boeing will also deliver 50 Apache AH-64E attack helicopters to the British Army under an agreement signed between the US and UK governments.

The collaboration between the UK and Boeing, announced on the opening day of the Farnborough International Airshow in Hampshire, is expected to create 2,000 jobs - doubling the US giant's UK workforce.

A new £100 million support and training base for the P-8A planes will be built at RAF Lossiemouth.

Boeing said it will make the UK its European base for training, maintenance, repair and overhaul across its defence fixed-wing and rotary platforms.

A further £365 million worth of aerospace research and development projects have been approved to boost the UK's position in the sector.

David Cameron visited the air show in one of his last official duties as Prime Minister and viewed a flypast featuring an F-35 Lightning II stealth fighter and the Red Arrows.

He said: "Whatever uncertainties our country faces, I want the message to go out loud and clear: The UK will continue to lead the world in both civil and defence aerospace.

"We aren't just open for investment, we are a place the global aerospace industry wants to do business - as Boeing's long-term partnership with the UK proves.

"It's also important to put Government investment where it counts. That's why we are jointly funding the new R&D fund with the aerospace industry and why I'm pleased we have today signed the contract for nine new P8 maritime patrol aircraft for the Royal Air Force, underlining the UK's commitment to spending on vital defence."

Mr Cameron joined Virgin Atlantic president Sir Richard Branson who signed a 4.4 billion US dollar (£3.4 billion) deal for 12 Airbus A350-1000 aircraft.

ADS Group, a trade association for the UK's aerospace industry, described the opening day of the show as a "strong start" with 191 orders announced for civil aircraft totalling £12 billion - worth £2.5 billion to the UK.

The organisation's chief executive, Paul Everitt, said: "The Farnborough International Airshow is where the global aerospace and aviation industry comes to meet and do business. Today's orders are good news for the UK economy.

"I was delighted to host the Prime Minister who was able to open our show and demonstrate the Government's continued support for the industry."

Boeing published a market forecast which stated that 39,620 new aircraft worth 5.9 trillion US dollars (£4.5 trillion) are expected to be bought over the next 20 years.

The figures represent a 4.1% increase on last year's forecast.

The supersonic F-35 jets are capable of short take-offs and vertical landing, and are one of the highlights of the seven-day show.

They are due to enter service with the Royal Navy and the RAF from 2018.