Apple said Imagination had known for nearly two years that it was winding down their relationship, despite the fact that Imagination's investors were shocked.

iPhone supplier Imagination Technologies Group Plc announced in April that Apple would no longer be using its graphics technology. The graphics provider's stock immediately collapsed more than 60 percent.

Apple claims it first informed Imagination in late 2015 that it would no longer be buying the U.K. company's latest technology. It continued using its older systems.

By 2016, Apple said it told Imagination it was further diminishing the relationship by initiating a clause in its contact that allows Apple to pay a lower royalty rate for using a smaller amount of intellectual property. By February of this year, Apple said it told Imagination it was ending the relationship altogether and would no longer be making any royalty payments as early as 2018.

Apple's statement clashes with Imagination's time line of events. On a conference call with investors this week, Imagination CEO Andrew Heath said the company was informed by Apple at the end of March "that they were certain" that products to be released in 2018 or early 2019 will no longer use Imagination's intellectual property.

Apple said Imagination had known for longer that the relationship was ending.

he two companies have worked together since the first iPhone was released in 2007, but now Apple is developing new graphics technology by itself.

Imagination has questioned whether Apple can develop new graphics technology without using its intellectual property.

The British company recently announced it's attempting to sell the company. Apple, which owns a stake in Imagination, isn't likely to make an offer, according to a person familiar with the matter.