Motorola has taken a 50 percent stake in UIQ, the Symbian user interface platform owned by Sony Ericsson, a move designed to increase its competition with the Nokia-owned S60 platform.

Motorola and Sony Ericsson will equally share ownership of UI Holdings, a set-up which the two companies contrasted with the rival S60 platform which remains wholly owned by Nokia. Sony Ericsson bought UIQ from its previous owner, Symbian, in November 2006.

The two companies will work together to develop the platform, and any further investors would also get an equal share of the company, said Ulf Wretling, general manager and head of content planning and management at Sony Ericsson. Other handset makers are invited to get on board - and the shares will be redistributed so any new partners get equal ownership, said Wretling.

Motorola's interest in UIQ could be an effort for the handset maker to produce more user friendly devices in the face of competition from Nokia and Apple, said Gerry Purdy, chief analyst at Frost and Sullivan. UIQ was developed early on as a touch-based user interface, and has been most widely seen in the series of Sony Ericsson phones leading from the P800 up to the current P1, and in the Motorola Z8 multimedia phone launched in summer. Touch screens have seen increased interest since the launch of Apple's iPhone.

The investment in UIQ could signal that Motorola plans to release more Symbian phones, Purdy said. The announcement could also mean that Motorola hopes to influence the development of UIQ such that the software could become compatible with other operating systems like Linux, he said.

UIQ is currently trailing a long way behind Nokia's S60 in the Symbian smartphone world, but the two companies have promised to promote it.

As well as having joint ownership behind it, UIQ will also support application portability, said Wretling: "We have been testing applications, and if they meet the developer guidelines, they can be written and then installed without change on both the P1 and the Z8. One size fits all. To my knowledge, that's different from other platforms." If the application is on a touch screen phone it will use that, otherwise it will use buttons, he said.

Motorola is better known for its Linux phones than its Symbian handsets. In fact, in 2003 Motorola appeared to move away from Symbian, selling its stake in the company. The move left Symbian wobbly. At one stage Nokia made a bid to control Symbian, since then Motorola has strongly supported Linux.

UIQ has grown from 160 employees to 350, and this deal will secure further growth and boost the UIQ ecosystem, said Johan Sandberg, chief executive of UIQ Technology.

Additional reporting by Nancy Gohring, IDG News Service