London-based BAE Systems, Japan's Mitsubishi Heavy Industries and Italy's Leonardo have agreed to deliver the concept phase requirements for next-generation combat aircraft, BAE Systems said Tuesday.

The three nations agreed in December 2022 to collaborate to build an advanced front-line fighter to enter service around the middle of the next decade.

The new Global Combat Air Programme (GCAP) agreement will support discussions to set out working arrangements and capability requirements for the aircraft, the BAE said.

Herman Claesen, BAE's GCAP leader, said a "high tempo of engagement with industrial and government partners in Italy and Japan" had been maintained since the launch of the program.

The three nations will update on the project's progress at London's Defence and Security Equipment International (DSEI) arms fair this week, BAE said.

The GCAP is expected to cost tens of billions of dollars, but the parties have not yet finalized how the budget will be split.

Britain's Defense Ministry had committed 2 billion pounds ($2.49 billion) to the project, formerly known as Tempest, before Japan and Italy joined.