They aren't expected to be announced until March, but details of the OnePlus 9 and 9 Pro smartphones have already surfaced online.

The last few days have seen details of the camera system appear, boasting a 48-megapixel primary sensor, and the first set of unofficial renders give a look at what the pair of phones are expected to look like.

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The OnePlus 9 and 9 Pro are due to rival premium 5G smartphones from Apple and Samsung. In the case of the former that means the iPhone 12 Pro and 12 Pro Max, while the latter will likely have launched its latest Galaxy S smartphone by then, expected to be called the S21 or S30.

Details of the OnePlus 9's camera come from 91mobiles.com, which claims it will have a 48-megapixel primary sensor producing 12MP images at a 6mm focal length There will also be a 48MP ultra-wide sensor, up significantly from the 16MP ultra-wide sensor of the OnePlus 8T.

A third image sensor will join those two lenses on the rear of the OnePlus 9, sources of 91mobiles claim, but it isn't clear what this will be. It could be a monochrome sensor exclusively used for producing black-and-white images.

The report also sheds some light on the OnePlus 9's specifications, which are said to include a Snapdragon 865 Plus processor with 8GB of RAM, and a 32-megapixel front camera with a hole-punch design. The battery is said to measure 5,000 mAh.

A day later, veteran smartphone leaker Steve Hemmerstoffer published a set of unofficial renders to the Voice social network, this time showing the larger OnePlus 9 Pro.

Not made by OnePlus itself, the renders are said to represent a phone currently in the prototyping stage of development, and as such Hemmerstoffer says: "The vast majority of its design is set in stone, but keep in mind that some small details, especially regarding the rear camera layout, may still change."

The renders show a handset with incredibly thin bezels at either side of the curved screen, giving the impression that the display stretches right across the front of the handset. The hole-punch camera mentioned earlier is set into the top-left corner, while the rear includes a OnePlus logo in the middle and a camera module with three sensors is in the top-left corner.

Hemmerstoffer says the screen measures 6.7 inches, slightly larger than the 6.55inch OnePlus 9. He also says the rear camera system could include four sensors instead of three, with the fourth potentially separating the 9 Pro from the regular 9.

"In the current prototype, two of these four lenses are enclosed within huge metal rings which protrude slightly from the main camera bump," Hemmerstoffer said, adding: "Two more smaller camera lenses as well as a flash, mic and some sensors are housed there as well. Unfortunately I don't know the detailed specs for each of these cameras and their sensors".

Finally, the smartphone leaker claims the OnePlus 9 Pro "will launch in March, and I can confirm this is correct."