The UK has signed an international treaty with Japan and Italy as the allies progress with a joint programme to develop a stealth fighter jet.

Defence Secretary Grant Shapps said the deal will see the headquarters for the Global Combat Air Programme (GCAP), the defence partnership between the three nations, based in the UK.

Prime Minister Rishi Sunak announced 12 months ago the collaborative international efforts to build military planes with supersonic capability and cutting-edge technology.

Called Tempest in the UK, they aim to take to the skies by 2035 and serve as a successor to the RAF Typhoon.

The Ministry of Defence (MoD) said the signing of the treaty in Tokyo on Thursday marked a “key stage” in the development of the next-generation fighter plane.

Speaking in Japan after signing the document alongside his counterparts, Japanese defence minister Minoru Kihara and Italy’s Guido Crosetto, Mr Shapps said: “This major programme with Japan, Italy and the UK working together will create an entirely new fighter stealth jet a 6th-generation jet, supersonic equipped with state-of-the-art censors, the standard for future combat air.

“No nation can do this alone – to this level of expertise, combining our skills and our equipment with our design and ability on production lines, using digital twinning, artificial intelligence, open architecture, robotic engineering and creating a truly cutting edge piece of kit.

He said the project will engineer “a new era of prosperity” for Italy, Japan, and the UK and create thousands of jobs for Britons.

“I know that in the United Kingdom, we already have 3,000 people working on this trans-national endeavour, and there’s a prospect for thousands more being employed across our three nations and, above all, it will strengthen our collective security,” he said.

“Our world-leading combat aircraft programme aims to be crucial to global security and we continue to make hugely positive progress toward delivery of the new jets to our respective air forces in 2035.

“The UK-based headquarters will also see us make important decisions collaboratively and at pace, working with our close partners Italy and Japan, and our impressive defence industries, to deliver an outstanding aircraft.”

When complete, the Tempest will boast a powerful radar that can provide 10,000 times more data than current systems, the MoD said.

Pilots will be able to use virtual reality in the aircraft’s digital cockpit, with vital information displayed directly in front of them.

The on-board weapons system will deploy artificial intelligence and machine learning to “maximise the effect” its arsenal can deliver, Mr Shapps’ department said.

Some £2 billion has been committed to the project by the UK Government up to 2025, with the investment announced in 2021 before the partnership with the other two nations on GCAP was confirmed.

The MoD awarded the contract to BAE Systems in collaboration with Leonardo UK, missile maker MBDA UK and Rolls-Royce, as well as industry partners from Japan and Italy.

Joint development of the aircraft is due to start in 2025.

The treaty confirms that the UK will host the joint GCAP government headquarters, with a Japanese chief executive at its helm at the outset.

Locations for the government HQ and a separate industry base, which will also be based in the UK and led by an Italian, are to be announced in “due course”, the MoD said, along with a timeline for opening.

The department said the offices will support UK jobs and facilitate close working with Japanese and Italian colleagues.

The government HQ will be responsible for delivering military capability, strengthening each country’s combat air industrial capability and achieving value for money, MoD officials stated, while the industry counterpart will oversee support and delivery of the programme.

The next step is for the treaty signed by the allies on Thursday to be sent to all three national parliaments for ratification.

Britain is undergoing a “tilt” towards the Indo-Pacific when it comes to foreign policy, with the Tempest programme and its alliance with Japan cited as part of a shift that recognises China’s growing influence in the region.

Mr Sunak has also developed a close political relationship with Italian premier Giorgia Meloni since entering Downing Street last year.

The pair have been united in taking a tough stance on asylum seekers arriving in Europe via unauthorised routes.

According to the Financial Times, Mr Sunak could make an appearance at a political festival in Rome on Saturday that has been organised by Ms Meloni’s right-wing Brothers of Italy party.