Italy must have an equal relationship in partnership with Britain and Japan to develop a new jet fighter. The country's defense minister, Guido Crosetto, told Reuters.

The three countries announced this month the creation of the Global Combat Aviation Program (GCAP) to develop a next-generation jet aircraft by 2035, which would combine the U.K.'s Tempest project with Japan's FX program.

Crosetto said Rome will make a final decision on how much to invest in the multibillion-dollar project once additional details are determined.

"Italy can only continue along this path if it has the same weight as Japan and Britain on technology, research and later, if it comes to that, on the results," he said in an interview, adding that he wanted a "33%-33%-33%" breakdown.

Britain's BAE Systems PLC, Japan's Mitsubishi Heavy Industries and Italy's Leonardo Defense Group will lead the development of the aircraft, while European missile manufacturer MBDA and other companies will also participate.

Crosetto said there should be no obstacle to joining forces with a competing European program, adding that GCAP should also look for new partners, especially in Europe. "I think the challenge is to accelerate significantly the research and technology part and then become attractive to other nations in the next two or three years," he said.