An Apple supplier that saw its business rocked by the iPhone maker’s plans to take its business elsewhere has fired back.
In an annual report filing on Tuesday, Imagination Technologies chairman Peter Hill called Apple’s announcement of plans to no longer use the U.K. company’s technology in its iPhones “highly regrettable.” CEO Andrew Heath called Apple’s move “unsubstantiated assertions” that have ultimately forced the company to change its tack. The “unsubstantiated assertions” ostensibly refer to Apple saying it would design replacement technology without providing proof of such a product.
With no apparent warning, Apple in April announced that it would stop using Imagination Technologies in the processor that powers its iPhones, and would therefore end its royalty payments to the company within the next two years. Soon after, Imagination Technologies shares plummeted more than 70%.
For years, Apple (AAPL) has relied upon Imagination Technologies (IGNMF) to power the graphics performance in its iPhone’s onboard processor. Apple accounts for about half of Imagination Technologies’ revenue, and the iPhone maker holds an 8% stake in the U.K. company. When Apple announced the move in April, analysts at Investec said that “the biggest risk to Imagination’s business model was realized.”
Get Data Sheet, Fortune’s technology newsletter
Apple said at the time that it would develop its own graphics chips to bundle with its iPhones.
Imagination in April responded by saying that it doubted Apple could develop its own graphics chips without violating the U.K. firm’s intellectual property. In May, Imagination said that it started a “dispute resolution procedure” to avoid lawsuits.
Still, those efforts have done little to mitigate Imagination’s problems, and the company in June announced that it was putting its business up for sale.
Imagination’s leaders were defiant in the annual report, saying that they still believe Apple would violate the company’s patents if the iPhone maker moves forward with its own chips. They acknowledged, however, that the dispute resolution hasn’t yielded any results, and the company is still up for sale.
Apple did not respond to a Fortune request for comment on Imagination’s comments.