Apple will have to shell out as much as $450m (£315m) as part of a settlement in the e-book price fixing case. The US Supreme Court has refused to hear its plea challenging an appellate court's decision, which in June 2015 had found Apple liable of engaging in a conspiracy that violated federal antitrust laws.

"With the Supreme Court's denial to review findings against Apple, consumers will receive an additional $400 million, reaching a total amount of more than $560 million when combined with settlements with the publishing companies – more than twice the amount of losses suffered by the class of e-book purchasers," Hagens Berman (attorneys) representing the class-action against Apple said in a statement.

"We're incredibly pleased to culminate this case for the millions of consumers who were forced by Apple and the publishing companies to pay inflated prices – skyrocketing up to 50 percent – for e-books," said Steve Berman co-founder of Hagens Berman.

"Under the proposed settlement, all consumers who purchased ebooks between April 1, 2010, and May 21, 2012, live in one of the states covered by the settlements, and make a claim will be compensated for alleged increases in the price of ebooks," the statement read.

In 2011, the law firm had filed a class-action lawsuit in a US District Court against Apple and five publishers including HarperCollins Publishers, Hachette Book Group, Macmillan Publishers, Penguin Group Inc and Simon & Schuster Inc. It was alleged that the companies were involved in practicing agency pricing model, where a few parties decide the price of the product to gain profits, which violates federal and state antitrust laws.

According to the lawsuit, while the Cupertino-headquartered smartphone-maker was trying to capture the market for iPad, it was facing tough competition from Amazon's e-book reader Kindle. Apple, apparently, collaborated with the publishers to increase the prices of e-books by as much as 50%. Via this agreement, Apple would give away 70% of earnings of e-books on iPads to publishers, if they increased prices. As a result, Amazon, which was earlier selling e-books for $9.99, was forced to increase prices to $12.99 and $14.99, else publishers would not share their books on the platform.

Amazon issued a statement saying, "We are ready to distribute the court-mandated settlement funds to Kindle customers as soon as we're instructed to move forward."