Apple said it tailored iPhone software to receive content from the superstar video-sharing website and play it on the device's 3.5-inch (8.89 centimeter) wide display. IPhones go on sale at US Apple and ATT stores June 29.

ATT is the exclusive service provider for the eagerly-awaited devices.

Apple also released an Apple TV software update that lets users of the boxes wirelessly route YouTube videos to their televisions.

"IPhone delivers the best YouTube mobile experience by far," Apple chief executive Steve Jobs said in a release.

"Now users can enjoy YouTube wherever they are -- on their iPhone, on their Mac (Macintosh computer) or on a widescreen TV in their living room with Apple TV."

Earlier this week, Cupertino, California-based Apple said it "significantly" increased iPhone battery life and upgraded the display from plastic to glass to improve clarity and reduce scratching.

A four-gigabyte model iPhone is priced at 499 dollars and an eight-gigabyte model is priced at 599 dollars.