Apple said it won't release Leopard, the next version of the Mac operating system (OS), in early June as planned, blaming the delay on the iPhone.

Apple said that it borrowed some key software engineering and quality assurance resources from its OS X team in order to keep the iPhone on track to ship in June. As a result, the company won't release Leopard as planned at its Worldwide Developers Conference.

Instead, Apple will show off a near-final version at the conference in early June and give beta copies developers. The final version of Leopard should now ship in October.

The iPhone contains "the most sophisticated software ever shipped on a mobile device, and finishing it on time has not come without a price," Apple said in a statement.

While unconfirmed rumours recently had the iPhone shipping 11 June, Apple now says it will ship in late June.

The company announced the iPhone earlier this year, unleashing a frenzy of anticipation among end users and competitors in the mobile phone sector. The phone will come with a touchscreen and music player.