A statement from the company said the device had been built after four years of research and six prototypes.

OPPO chief product officer Pete Lau said: "New form factors are ushering in an exciting new time in smartphone technology.

"OPPO has invested a significant amount of time and effort into coming up with a better approach to a foldable smartphone, experimenting with a range of form factors, hinge designs, display materials and aspect ratios, to create a new device that meets the needs of more users.

"With the OPPO Find N, we aim to change people's perceptions about what a smartphone can offer and begin making foldable devices more accessible to an even larger audience."

The OPPO Find N is built atop a Snapdragon 888 SoC, and has 12 GB of LPDDR5 RAM and 512 GB of UFS 3.1 storage.

Users can switch between a 7.1-inch inner display and a 5.49-inch outer display.

The device has a 4500 mAh battery and 33W SUPERVOOC flash charging optimised to charge to 55% in 30 minutes and to 100% in 70 minutes.

The Find N also has 15W AIRVOOC wireless charging (compatible with standard Qi) and 10W reverse wireless charging. It has a side-mounted fingerprint scanner housed in the power button, a dual speaker system and Dolby Atmos support for more lifelike sound.

The device will be sold in China from 23 December, with launch dates for other countries not available at the moment.

The 8GB memory and 256GB storage device will retail for 7699 yuan (approximately A$1684), while the 12GB/512GB version will cost 8999 yuan (approximately A$1970).