Google stepped up its assault on the smartphone and tablet computer market yesterday with the £7.7 billion acquisition of handset-maker Motorola.

The search engine group is to pay $12.5 billion for Motorola Mobility in a deal which gives it direct control over one of the largest manufacturers of mobile phones running Android, Google’s own operating system.

The price, a 63 per cent premium to the value of Motorola Mobility at the end of last week, makes the deal the largest ever undertaken by the California-based company and was hailed by Google chief executive Larry Page as a “natural fit”.

Motorola Mobility is already a partner of Google, but will remain as a separate business and licensee of Android, which will also remain an open platform.

Analysts said yesterday’s acquisition marks a change of emphasis for Google as the battle with Apple and Asian rivals intensifies in the booming smartphone and tablet market.

Predictions are for the tablet computer market to grow more than 10-fold by 2015, with tablets running on Android tipped eventually to match or even overtake the current market leader, Apple’s iPad.

Patents are increasingly becoming a key weapon in the battle. Google recently lost a bidding battle over thousands of wireless patents owned by Nortel Networks to a consortium of Microsoft, Apple and Blackberry owner Research In Motion.