Amazon had sold out of its basic Kindle electronic book reader on Wednesday with no indication as to when deliveries would resume.
Amazon.com listed the 189-dollar Kindle as "temporarily out of stock."
The Seattle, Washington-based online retail giant was still taking orders, however.
"Order now and we'll deliver when available," it said. "We'll e-mail you with an estimated delivery date as soon as we have more information."
The larger-screen model of Amazon's popular e-reader, the Kindle DX, was available for purchase.
There was no immediate reply to an email to Amazon from AFP asking when deliveries of basic Kindles may be resumed.
Facing competition from Apple's new iPad tablet computer, Amazon dropped the price of its basic Kindle last month to 189 dollars.
Amazon does not release sales figures for the Kindle, but says it has been the company's best-selling item for two years.
On July 1, Amazon unveiled a new Kindle DX and cut the price to 379 dollars from 489 dollars.
Apple's cheapest iPad costs 499 dollars and features a color e-reader compared with the black-and-white Kindle, which is devoted exclusively to digital books.
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