It's almost Orwellian.

Owners of Amazon.com Inc.'s (AMZN) Kindle electronic book reader are up in arms for the second time this week, this time because the online retailer deleted titles by author George Orwell from their devices without permission.

Starting on Thursday, Kindle owners began noticing that Amazon had deleted Orwell's "Animal Farm" and "Nineteen Eighty-Four" from their devices. The company credited customers for the books, but the deletions prompted an outcry on Amazon's Kindle forum.

Amazon on Friday acknowledged it had deleted the books from its customers' Kindles. The retailer said it deleted the works because they were improperly added to Amazon's catalog through a self-service platform by a third-party that didn't have rights to them.

"When we were notified of this by the rights holder, we removed the illegal copies from our systems and from customers' devices, and refunded customers," said Drew Herdener, an Amazon spokesman, in an email. "We are changing our systems so that in the future we will not remove books from customers' devices in these circumstances."

The move prompted a spate of angry messages on the Kindle forum. One customer said Amazon's actions were like "a Barnes & Noble clerk coming to my house when I'm not home, taking a book I bought from them from my bookshelf and leaving cash in its place."

The incident is the second black eye for the Kindle this week.

On Tuesday, a customer filed a lawsuit claiming that cracks appeared on his Kindle and its screen froze only a few months after purchase.

The plaintiff, who was seeking class-action status and argued total damages could exceed $5 million, complained the company told him he would have to pay $200 for repairs. Amazon moved quickly to diffuse the situation by announcing it would provide free replacements to customers whose Kindles had cracked.

Shares in Amazon closed down 0.3% at $85.85 on Friday.

-By Scott Morrison, Dow Jones Newswires; 415-765-6118; scott.morrison@dowjones.com