Amazon.com Inc., the world's largest Internet retailer, on Wednesday reported second-quarter profit rose 29 percent, beating analysts' expectations, citing stronger sales in the U.S. and abroad amid concerns of a worldwide economic slowdown.

The Seattle-based Internet retailer reported that net income in the first quarter rose 30 percent, to $143 million, or 34 cents a share, from the year-ago quarter.

The company said sales climbed 37 percent, to $4.13 billion, above Wall Street expectations who predicted net income of 32 cents a share and revenue of $4.08 billion, according to a survey of analysts by Thomson Financial.

The company said its growth was driven primarily from a boost in its Amazon Prime discount shipping program, helpful foreign exchange rates and an increase in sales from third-party retailers who sell on their site.

Our sales growth this quarter was driven by low prices and millions of in-stock items available for immediate shipment, said Jeff Bezos, founder and chief executive of Amazon.com. We're grateful to our customers.

Amazon.com shares fell as low as $77 in after-hours trading after closing at $81.

Looking ahead to the next quarter, Amazon said it expects net sales of between $3.87 billion and $4.1 billion and for fiscal 2008, it expects net sales to total between $19.1 billion and $20 billion. Analysts expect second-quarter net sales of $3.84 billion and fiscal 2008 sales of $19.29 billion.

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