Shares in Imagination Technologies, a Hertfordshire-based company, have plummeted almost 70 per cent after Apple said that it won’t be using the group’s technology in future.

In a regulatory filing on Monday, Imagination said that Apple, which is its largest customer, had said that that it will not use the group’s intellectual property in its new products in 15 months to two years’ time.

Apple has for years used Imagination as a supplier for its phones, tablets, iPods, TVs and watches. But Imagination said that Apple is now “working on a separate, independent graphics design in order to control its products” and that it will be “reducing its future reliance on Imagination’s technology”.

Imagination responded to the news by saying that Apple had “not presented any evidence to substantiate its assertion that it will no longer require Imagination’s technology, without violating Imagination’s patents, intellectual property and confidential information”.

“This evidence has been requested by Imagination but Apple has declined to provide it,” Imagination said.

The UK company said that it believes that it would be “extremely challenging” for Apple to replace the technology that Imagination supplies, “without infringing its intellectual property rights” and that “accordingly Imagination does not accept Apple’s assertions”.