Apple's latest iPhone with its A18 chip, which is set to be unveiled at an event on Monday, has been developed using SoftBank-owned Arm's newest V9 chip design, the Financial Times newspaper reported on Saturday.

Apple is set to host its fall event on September 9 at its headquarters in Cupertino, California, where it will likely unveil a series of new iPhones and updates to other devices and apps.

Apple signed a deal with Arm in September last year that "extends beyond 2040" in a boost for Arm's chip technology. Arm had said in July that its V9 chip accounts for 50 percent of smartphone revenue.

Arm owns the intellectual property behind the computing architecture for most of the world's smartphones, which it licenses to Apple and many others. Apple uses Arm's technology to design its own custom chips for its iPhones, iPads, and Macs.

The two companies have a long history. Apple was one of the initial companies that partnered to found the firm in 1990, before the release of its "Newton" handheld computer in 1993, which used an Arm-based processor chip.

The Newton flopped, but Arm went on to become dominant in mobile phone chips because of its low power consumption, which helps batteries last longer.