Amazon said Thursday that it is selling more than one million Kindles a week and the new Kindle Fire tablet computer is its top-selling item.

"Kindle Fire is the most successful product we've ever launched -- it's the best-selling product across all of Amazon for 11 straight weeks," Amazon Kindle vice president Dave Limp said in a statement.

"We've already sold millions of units, and we're building millions more to meet the high demand... In fact, demand is accelerating -- Kindle Fire sales increased week over week for each of the past three weeks."

Amazon, which rarely releases Kindle sales figures, said it had sold well over one million Kindle devices a week for the past three weeks.

Besides the Kindle Fire, which went on sale in mid-November, Amazon offers a range of Kindle electronic book readers.

"Our family of Kindle e-ink readers are close behind Kindle Fire on the Amazon.com bestseller list," Limp said. "In fact we've seen many customers buy two Kindles -- both a Kindle Fire and a Kindle or Kindle Touch -- this holiday season."

The Kindle Fire costs $199, less than half the price of the cheapest iPad from tablet market leader Apple.

It has a seven-inch (17.78-centimeter) screen, smaller than the iPad's 9.7 inches (24.6 cm), connects to the Web using Wi-Fi and is powered by Google's Android software.

It does not have a camera or the 3G connectivity featured on other tablets but it gives buyers easy access to Amazon's online store, which sells books, music, movies, television shows, games and other content.

Amazon said Monday that it will release a software update to improve the performance of the Kindle Fire within two weeks.

The company sidestepped questions over whether the upgrade was a response to complaints about Internet browsing speed and wireless connectivity since the device went on sale.

"As with all of our products, we continue to make them better for customers with regular software updates," Amazon said.