Apple's long-rumoured 12.9-inch iPad Pro is reportedly being delayed.

As Digital Spy reports citing Bloomberg, the tablet will go into production around September time.

Sources close to the company claim that Apple was planning to start making its new larger iPads this quarter but the process is being held up by the supply of display panels.

Also referred to as the iPad Air Plus, the device is expected to launch with a next-generation A9 processor on board and retain the Touch ID fingerprint scanner of previous iOS hardware.

The large-screen iPad was originally tipped to break cover alongside the iPad Air 2 and iPad mini 3 in October 2014, but Apple is yet to officially confirm its existence.