British chip designer Imagination Technologies announced it had put itself up for sale on Thursday, weeks after the group launched a formal dispute against Apple.

While Imagination said it was "progressing well" having attracted buyer interest, the U.K.-based firm confirmed it "remains in dispute with Apple". In April, the Silicon Valley giant announced it would no longer need to use Imagination's intellectual property in its products from 2019 onwards.

Imagination creates the technology for electronic chips, focusing specifically on graphics, video and visual products. For several years, this technology has been used to provide the graphics in Apple's iPhone, iPad and iPod products; however, the California-based technology giant told Imagination that it is developing its own "independent graphics design" and will be "reducing its future reliance on Imagination's technology."

Shares of the group more than halved in April after Apple announced it would stop using its products, with the tech giant accounting for about half of Imagination's revenues. In the group's latest annual report, it described the Apple contract as "essential."

On Thursday, Imagination's shares soared over 20 percent after it said it had "received interest from a number of parties for a potential acquisition" over the last few weeks.

—CNBC's Karen Gilchrist contributed to this report.