Sony has cut its sales expectations for the PSP for the financial year starting in April 2006 from 12 million units to only 9 million, with the runaway success of the Nintendo DS only partly to blame.

Robert Wiesenthal, chief financial officer of Sony Corporation of America believes that the PSP is suffering from not having a defining title that will galvanise the platform.

"Clearly on the software side, any real killer title will galvanize the sales," said Wiesenthal. "There have been a number of titles that have been terrific, but not the one title that defines the product."

Hiroshi Kamide, director of the research department at KBC Securities Japan shares similar views, pointing to software as the key driver of hardware sales.

"You don't see any million-seller games for the PSP but you do hear about them for the Nintendo DS," said Kamide. "The big problem is that while it's a wonderful-looking machine with a great display, the games are not so different from those you play at home on the PlayStation 2. Most of the software is knock-offs of PlayStation 2 titles and that won't do Sony any favours."

Sony recently lowered the price of the PSP to £129.99 and announced a selection of budget titles. The platform holder has also stated that a newly designed PSP is in the works, but no release date has been announced.