Apple said on Thursday it was delaying the release of its new computer operating system code-named Leopard, focusing on the iPhone release late June.

The company said its eagerly anticipated iPhone was on schedule to ship in late June as planned after passing several of its required certification tests.

But it said delivering the phone on time contributed to the delay of the next version of its OS X operating system, code-named Leopard, until October because the company said it had to divert resources to the iPhone.

"iPhone contains the most sophisticated software ever shipped on a mobile device, and finishing it on time has not come without a price -- we had to borrow some key software engineering and ... resources," Apple said in a statement.

Leopard is expected to boast new features including a file back-up feature called "Time Machine" and improvements to its e-mail and instant messaging software. Another feature allows users to move from their standard desktop view to an archival view showing every change made to a particular file.

Apple said Leopard's features would be complete in early June ahead of its worldwide developers conference but that the product would not be ready for release. Instead, the company said it plans to give developers a test copy and ship Leopard in October.

The delay follows Apple's January debut of its much-anticipated take on the smart phone, combining a phone, an iPod and instant messaging in a sleek device with a large screen.