Sony Ericsson, the world's fourth largest mobile phone maker, is still mulling over the idea of a mobile phone based on Sony's PSP (PlayStation Portable) console. We previously reported the concept was under evaluation.

The firm's outgoing president, Miles Flint, said in an interview that the technology behind a combined mobile phone and PlayStation unit is already developed - it just needs refining. "It's an area of possible future activity," Flint told the Financial Times. He will step down as Sony Ericsson's president in November.

"We need to make sure that it is a credible phone, and be sure we are justified in putting that identity on it."

He didn't speculate on when such a handset could be available but said it is likely to be a while yet.

Sony Ericsson has had huge success with previous handsets linking up with Sony brands such as the Walkman and CyberShot series. In Japan, the firm is already trialling a Bravia-branded handset for mobile TV.