Apple Inc. said it sold more than 5 million of the iPhone 5 in three days, shattering a record set by the previous model, as customers lined up in stores from Sydney to San Francisco for the company's latest handset.

A successful debut for the iPhone, responsible for about two-thirds of profit, is crucial to fueling the growth that transformed Apple from a niche computer maker into the world's most valuable company. Last year, the iPhone 4S sold 4 million units in its debut weekend.

Demand for the iPhone 5, with a bigger screen and faster wireless speeds, gives Apple a boost over rivals including Samsung Electronics Co. that use Google Inc.'s Android mobile software. The device went on sale Sept. 21 in the U.S., Australia, Canada, France, Germany, Hong Kong, Japan, Singapore and the U.K. It will be in 22 more countries on Sept. 28. Apple plans to have the iPhone in more than 100 countries by the end of the year, the fastest introduction in the company's history.

The shares of Cupertino, California-based Apple fell in early trading after closing at $700.10 in New York on Sept. 21. The stock has gained 73 percent this year.

Gene Munster, an analyst at Piper Jaffray Cos., had predicted Apple would sell as many as 10 million of the iPhone 5 during the opening weekend.

Sales from the weekend will be included in Apple's financial results for the fiscal fourth quarter, which ends Sept. 30. The company is expected to report profit of about $8.3 billion on sales of $36.1 billion, according to the average of analysts' estimates compiled by Bloomberg.

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Besides the outsize screen and faster data speeds, the iPhone 5 comes with a more powerful microprocessor and lightweight body design. Software changes include new mapping and navigation features, a change Apple made to replace Google's maps application. Some users and technology gadget reviewers have criticized the new navigation features.

In addition to the iPhone release, Apple also introduced a new version of its mobile operating system, called iOS 6. The update was downloaded by more than 100 million customers, Apple said.