Technology firms like Nokia and Microsoft are rushing to open their mobile software stores, hoping to follow the runaway success of Apple's online App Store.

The focus of the cellphone market has been shifting to software development since Google and Apple entered the mobile market in the past two years.

Research firm Strategy Analytics forecasts the value of the mobile content market - including downloadable games, ringtones, wallpapers, video, mobile TV, text alerts and mobile web browsing - to grow 18 per cent to €51.8 billion this year.

The company will hold a press conference today.

Nokia promised in early December to launch its own download store "soon", as the Finnish firm merges its software Download! store with free media sharing site Mosh and widget service WidSets.

Microsoft Corp. is also planning an "online bazaar" for applications running on its Windows Mobile operating system, according to the Wall Street Journal.

Blackberry-maker Research in Motion said last year it plans to launch its app store early this year.

Apple's App Store has proved to be popular with iPhone users, and helped spawn an entire industry of entrepreneurs who design the programmes which can then be downloaded by consumers. Apple said last month a total of 15,000 applications are available and downloads have hit 500 million in six months.

"Apple has proved that what the mobile industry has been missing is the supermarket," said Eric Klein, vice president for marketing of Java at Sun Microsystems.

CCS Insight analyst Ben Wood said: "The tremendous success of Apple's App Store has underlined the importance of this distribution channel."

US software firm Amdocs, software and services provider for telecom operators, said it would unveil its white-label application store offering - which enables the buyer to brand the store - to carriers at the trade show this week.