(Reuters) - Amazon.com Inc said on Thursday that its Kindle Fire tablet accounts for 22 percent of U.S. tablet sales and that the device is sold out.

The tablet hit stores last November at a cost well below that of Apple Inc's market-leading iPad.

Amazon is holding a press event next week in Santa Monica, California, fueling speculation it will launch new tablet devices.

Since the Kindle Fire launch last year, Google Inc has introduced a seven-inch tablet called Nexus 7, which has been selling well. Barnes & Noble Inc's Nook Tablet, introduced last autumn, has also been popular.

Amazon said its Kindle Fire is sold out, but its statement did not say when the device would be back in stock, nor how many Amazon has sold.

Since the launch of the tablet last year, Amazon's top-selling products have all been digital products such as music, videos and movies, Amazon said.