Amazon.com has deleted two George Orwell books from Kindle devices of customers who had bought the books, the U.S. online content seller said.

The Kindle users had purchased digital editions of "1984" and "Animal Farm" from a company that did not have the rights to the titles, The New York Times reported Friday.

The titles were added to Amazon's Kindle store by a company that did not have rights to them, Amazon.com spokesman Drew Herdener told the newspaper.

"We are changing our systems so that in the future we will not remove books from customers' devices in these circumstances," Herdener said.

Kindle owners whose copies of "1984" and "Animal Farm" were deleted said they bought them from the digital publisher MobileReference.

The U.S. publisher Houghton Mifflin Harcourt was offering an authorized digital version of "1984" Friday night but "Animal Farm" was not available, the Times said.

Charles Slater of Philadelphia, who said he bought "1984" for 99 cents, found the situation ironic.

"Of all the books to recall," he said.