Apple is facing a bill for $862 million (£565m) after losing a lawsuit over a patent infringement.

The University of Wisconsin successfully sued the technology giant over the use of its microchip technology. The university patented the chip, which improves power efficiency, in 1998.

Apple has used the tech in the iPhone 5s, 6 and 6 Plus models. And a new lawsuit has been filed for its use in the new 6S and 6S Plus models.

According to the filing, the University of Wisconsin said it offered Apple the chance to license the patent, effectively giving the company permissions to use the microchips in exchange for a fee. It said that Apple rejected such offers.

The university claims that Apple knowingly infringed its patent. If judged to be true by the courts, Apple will face a larger fine. Apple's fine will be determined at a later date.