Apple has not yet officially launched the iPad in Asia, but that hasn't stopped a booming "grey market" trade in the world's most talked-about high-tech gadget.

The company said that it had sold a million iPads in just 28 days, and thousands of those clever little black slabs of glass and aluminium made it to Asia.

From Singapore to Seoul, Bangkok to Beijing, iPads are on sale - for a substantial mark-up on the US retail price.

In Hong Kong, computer malls are doing brisk business.

"We get them from the US," Carl Lee, a salesman at a computer shop in Mongkok Computer Centre, said.

"But if you want one, get one quick - Apple is restricting buyers to only two iPads per credit card in the States and we don't know how much longer we can get them."

The store could get 15 of the basic 16-gigabyte (GB) models "within a day", he said, for 5,700 Hong Kong dollars each - around US$730.

The same model retails in the United States for US$499.