Apple Inc on Tuesday introduced models of its popular iPod touch handheld computer and iPhone with double the memory available in previous versions.

Apple, which said in January it had sold more than 4 million iPhones since sales began last June, says the iPhone will now also sell with 16 gigabytes of memory.

The iPod touch, a wireless touch-screen device that plays music and videos, adds a 32 gigabyte model. Both devices will sell for $499, Apple said.

Apple will continue to sell its iPhone with 8 gigabytes of memory for $399, and two lower-capacity versions of the iPod touch, 16 gigabytes and 8 gigabytes, for $399 and $299, respectively.

The updated models come amid a slump in Apple's stock, due to fears that a U.S. recession could make consumers less likely to buy iPods or iPhones. The stock, which closed on Tuesday at $131.65 on Nasdaq, is down more than 33 percent so far this year.

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