Motorola is to acquire a 50 per cent interest in the parent company of the developers of the UIQ mobile operating system.

The terms of the agreement to share ownership of UI Holdings BV, which is currently wholly owned by Sony Ericsson, were not disclosed.

However, it was revealed that Motorola and Sony Ericsson will work together and jointly invest in the development of the UIQ open user interface platform.

"UIQ has benefited greatly from our partnership with Sony Ericsson and we are confident that Motorola's interest will create new and important growth opportunities for UIQ, our customers, employees and consumers around the world, " said Johan Sandberg, chief executive at UIQ Technology.

The move follows Sony Ericsson's acquisition of UIQ Technology from Symbian in February 2007.

"This is an important transaction that demonstrates the increasing importance of open operating systems for all handset vendors," said Miles Flint, president of Sony Ericsson Mobile Communications.

Both companies have agreed that UIQ will be vendor and chipset independent, and that the platform will be licensed on equal terms to all mobile device vendors in the industry.

Thanks to its single code base, UIQ offered the industry's first touch-screen interface back in 2002 and now supports Qwerty and numerical keyboard configurations as well as finger touch data input.

Both companies have been UIQ licensees for many years and have launched several Symbian/UIQ-based products.

The pair have confirmed that they aim to expand ownership of UIQ in the future, and hope to make further announcements about new shareholders and licensees in due course.

Motorola's investment in UI Holdings BV is subject to customary regulatory approval and is expected to be completed by the end of the year.