Apple said it sold 2 million iPads since launching the touch-screen tablet in the United States nearly two months ago and taking it to nine international markets this past weekend.
The company did not give a geographic breakdown of sales in its statement, but had previously said it sold 1 million iPads in the first month after the US launch on April 3 - passing that milestone faster than the iPhone. An Apple representative was not immediately available for comment.
Fans mobbed Apple's international stores on Friday when the iPad went on sale in Australia, Canada, France, Germany, Italy, Japan, Spain, Switzerland and the UK.
Apple delayed the international launch by a month as it had difficulty meeting demand for the device, which has received high marks for videos and games, reading electronic books and magazines, and general web browsing.
Apple said the iPad will be shipped to nine more countries in July, including Mexico, Austria and Ireland. Pricing for these markets will be announced later, it said.
RBC Capital Markets has estimated iPad's total shipments to reach 8.13 million units worldwide by the end of the year - which would translate into at least $4 billion (£2.76 billion) of revenue.