Washington, Jun 11 (IANS): Apple Inc. has unveiled an operating system for its iPhones and iPads that will radically overhaul how users' touchscreens look, a top company official said.

Besides the new system, iOS 7, also unveiled was a refreshed MacBook Airs. The company announced an iTunes Radio streaming-music service and a sneak peek at a new Mac Pro that would be the most powerful computer Apple has ever made.

Unveiling Apple's first major product event in nine months in California Monday, chief executive Tim Cook called it "the biggest change to iOS since the introduction of the iPhone".

Developers assembled for the week-long conference got the first look at a major reworking of Apple's mobile operating system, due in September, CNN reported.

iOS is home to more than 900,000 apps that collectively have earned independent developers $10 billion, according to Apple.

The mobile design, overseen for the first time by new iOS boss Jony Ive, includes new typography, redesigned icons and a new colour palette. The pool-table green background on Game Centre is gone.

Siri, Apple's voice-activated "digital assistant", has become more diverse. Users will be able to choose a male voice -- Siri has been solely a "she" so far -- and can ask it to perform basic tasks like playing a voicemail or turning down the brightness on an iPhone or iPad's screen.