Apple's new iPad went on sale in 25 countries internationally on Friday, but the United States is still the cheapest place to buy the latest version of the tablet computer.

Prices in the United States, where the iPad 2 has been on sale since March 11, start at $499 for the most basic model -- with 16 gigabytes of storage and Wi-Fi only connectivity -- while the same model in Denmark costs the equivalent of $702.

Customers lined up in their hundreds outside Apple stores in Europe and Asia, many waiting overnight or longer, to get their hands on an iPad 2 amid fears of shortages.

In Hong Kong, where the iPad 2 will not officially go on sale until next month, enterprising Chinese businessmen were already selling devices bought in the United States for up to HK$ 15,000 ($1,900).

In the United States, sales tax varies from state to state between zero and 13.725 percent, giving a maximum price to the consumer of $567 and an average of $547.

In the euro zone, the basic iPad 2 is selling at 479 euros ($678) in most countries, although it is slightly more expensive in France and cheaper in Luxembourg.

Unusually, it is cheaper in Britain than in continental Europe, selling for 399 pounds ($642).