A group of leading mobile phone companies are teaming up to develop a common operating system in an attempt to thwart competition from the Google-backed Android project.

Nokia, Symbian, Sony Ericsson, Motorola and others have formed the Symbian Foundation and pledged to create a common unified interface and application platform for mobile phones and other devices which will be available to developers under a royalty-free open source licence.

Nokia has also bid to purchase the remaining 52 per cent of Symbian that it does not already own for €264m. Other members of the foundation include carriers and mobile operators AT&T, NTT DOCOMO and Vodafone, as well as device manufacturers LG Electronics, Samsung Electronics, STMicroelectronics and Texas Instruments.

The Symbian Foundation will eventually integrate the Symbian, S60 (Nokia), UIQ (Sony Ericsson) and MOAP (NTT Docomo) mobile platforms under a single framework to speed up application development and simplify platform choices for mobile operators.

Selected open source components, including unified interface, middleware and operating system tools, will be gradually released under the Eclipse Public Licence 1.0 between now and 2010.

But applications developed now will be forward compatible to ensure they run on the new platform, said Mats Lindhoff, Sony Ericsson's chief technology officer.

The Symbian Foundation framework will compete for mobile developers' attention with rival open source platforms based on Linux, such as the LiMO Foundation and the Google backed Open Handset Alliance, also known as Android. Proprietary mobile platforms, including Microsoft's Windows Mobile and Apple's iPhone, are also starting to gain more market share.

The Symbian mobile operating system has shipped on 200 million devices worldwide since its first appearance 10 years ago, and there are an estimated four million software developers worldwide already building Symbian applications, said Symbian chief executive Nigel Clifford.