Amazon crowned a new bestseller on Thursday -- the Kindle, its electronic book reader.

"Kindle has become the number one bestselling item by both unit sales and dollars -- not just in our electronics store but across all product categories on Amazon.com," said Amazon founder and chief executive Jeff Bezos.

In keeping with previous practice, Bezos declined to reveal sales figures for the Kindle, but Forrester Research estimates the device has a nearly 60 percent share of the US market followed by the Sony Reader with 35 percent.

Forrester estimates that three million e-readers will be sold in the United States this year, up from a previous forecast of two million units, and for e-reader sales to double to six million units next year.

Bezos also announced that the price of a new international version of the Kindle, which is designed to synch with telecom networks in 100 countries, was being cut to 259 dollars from 279 dollars.

The Bezos statements came as his Seattle-based company reported a 68 percent rise in net profit in the third quarter to 199 million dollars, or 45 cents per share, better than the 33 cents per share forecast by Wall Street analysts.

Revenue increased 28 percent to 5.45 billion dollars during the quarter which ended on September 30.

Amazon shares soared 14.77 percent in after-hours electronic trading to a record 107.25 dollars.

Unlike eBay, which unveiled a cautious outlook for the holiday season the previous day, Amazon delivered an optimistic sales forecast for the Christmas period.

It said it expected fourth-quarter sales of between 8.1 billion dollars and 9.1 billion dollars, an increase of between 21 percent and 36 percent over last year.

Amazon said North America sales rose 23 percent in the quarter to 2.84 billion dollars while international sales from its British, German, Japanese, French and Chinese sites rose 33 percent to 2.61 billion dollars.

It said worldwide media sales, which include music, books and other items, grew 17 percent to 2.93 billion dollars.

Sales of electronics and other general merchandise sales climbed 44 percent to 2.36 billion dollars.

Amazon also said that the Kindle book store has increased its number of titles to more than 360,000 books including 101 of the 112 New York Times bestsellers.

Bezos told Amazon's annual shareholders meeting in May that the company may never reveal Kindle sales figures. "Our point of view on that is that there can often be a competitive advantage in keeping the numbers close," he said.

But Amazon is not the only firm trying to shake up the market for electronic books.

Google is pressing ahead with plans to digitize thousands of books and on Wednesday hardware firm Hewlett-Packard said it would get in on the action, stepping up its out-of-print book publishing business and taking on Google.

The US computer giant announced Wednesday it has teamed with the University of Michigan to offer print versions of more than 500,000 out-of-copyright books in the school's library.