Online retailing giant Amazon said Monday that sales of its Kindle e-readers and tablets quadrupled on Black Friday over the previous year's annual pre-Christmas national shopping orgy.

The company gave no specific data on Kindle sales last Friday, but said its new tablet computer, the Kindle Fire, was also the bestselling product on Amazon.com.

"Even before the busy holiday shopping weekend, we'd already sold millions of the new Kindle family," Dave Limp, vice president of Amazon's Kindle division, said in a statement.

"Black Friday was the best ever for the Kindle family -- customers purchased four times as many Kindle devices as they did last Black Friday -- and last year was a great year," he said.

Amazon has slashed prices of the Kindle e-readers and set a below-cost price for the Fire -- a rival of Apple's iPad -- with an eye at boosting sales of e-books, music and movies from its online store, analysts say.

"The Kindle Fire, at a retail price point of $199, is sold at a loss by Amazon, just as the basic Kindle is also sold at a loss at the current $79 retail price point," IHS iSuppli's Andrew Rassweiler said earlier this month.

"Amazon makes its money not on Kindle hardware, but on the paid content and other products it plans to sell the consumer through the Kindle," Rassweiler said.