NEW YORK (AP) -- Apple Inc. said Monday that it sold more than 1.7 million units of its new iPhone model in the first three days, making it the most successful product launch in the company's history from the standpoint of sales.

The iPhone 4 went on sale Thursday in the U.S., Britain, France, Germany and Japan. High demand for the model caused shortages and unruly crowds at some stores.

"This is the most successful product launch in Apple's history," said Steve Jobs, Apple's CEO. "Even so, we apologize to those customers who were turned away because we did not have enough supply."

Some stores sold out within hours. Analysts have said Apple is having a hard time procuring enough parts for the phone, such as its new higher-resolution screen. Apple has said the white iPhone it plans to produce has been more challenging than expected and won't be available until late July. Only black models went on sale Thursday.

Apple sold more than 1 million units in the first three days when it launched last year's model, the 3GS. Canada, Italy, Spain and Switzerland were then among the launch countries, but Japan was not.

Apart from the sharper screen, the iPhone 4 features a slimmer body and faster processor than the previous model, among other changes.

Shares of the Cupertino, Calif.-based Apple rose $1.52, or 0.6 percent, to $268.22 in morning trading Monday.