San Francisco, May 2 : Apple reportedly registered profits as high as 78 per cent from its App Store in 2018 and 2019, an expert witness for Epic Games has testified, as the Cupertino-based tech giant and Fortnite game developer prepare for a legal battle in the US beginning Monday. According to The Verge, expert Ned Barnes testified that "information from Apple's Corporate Financial Planning and Analysis group show the App Store had a 77.8 percent operating margin in 2019, and 74.9 percent in 2018". Apple has contested that interpretation of the data, saying "we don't have a separate profit and loss statement for the App Store". "Epic's experts calculations of the operating margins for the App Store are simply wrong and we look forward to refuting them in court," an Apple spokesperson was quoted as saying in the report on Saturday. Epic Games will defend its stance during a lawsuit hearing against from May 3. The companies got involved in a legal battle over the use of an in-game payment system. While Epic Games argues about Apple's monopoly over the app market and treats 30 per cent standard fee amount to anti-competitive behaviour that must be regulated by antitrust law, Apple contends that "the whole antitrust allegation and associated dust-kicking is little more than a PR stunt". Apple CEO Tim Cook as well as Epic Games Founder and CEO Sweeney may testify in the trial. For Apple, the proposed witness list also includes Software Engineering Senior Vice President Craig Federighi and Apple Fellow, Phil Schiller. On team Epic, the Vice President Mark Rein is also included as witness, besides Sweeney, according to earlier media reports. The Fortnite game was removed from App Store in August of last year after the company allegedly violated rules by adding an in-game payment system aimed at depriving Apple of its commission on in-app purchases from App Store. /IANS