Sony, in a challenge to Amazon's Kindle, unveiled plans on Thursday to do away with the proprietary software on its electronic Sony Reader and convert its e-book store to an industry standard format.

The Japanese electronics giant said the move "allows Sony to make its e-book store compatible with multiple devices and its Reader devices open to multiple sources for content."

Sony said it would convert its e-book store to the open ePub format by the end of the year as part of "an effort to take the confusion out of digital book formats."

Sony said it would drop proprietary copy-protection software on the Reader in favor of a cross-platform anti-copying software solution developed by Adobe.

Sony's move is seen as a direct challenge to Amazon, whose electronic books can only be read on the Kindle or on an Apple iPhone using Kindle software.

"Consumers should not have to worry about which device works with which store," Steve Haber, president of Sony's Digital Reading Business Division, said in a statement.

"With a common format and common content protection solution they will be able to shop around for the content they want regardless of where they get it or what device they use," he said.

The ePub format was developed by more than 60 companies and organizations and has received the support of the International Digital Publishing Forum.

Sony noted that dozens of publishers are producing e-books using the ePub standard.

Amazon does not reveal sales figures for the Kindle and chief executive Jeff Bezos said at the annual shareholders meeting in May that the company may never reveal the numbers.