The global mobile app market is increasing from $4.7 billion in 2009, and will likely be worth $16.6 billion by 2013.

According to a report from Brand Republic, a study compiled by wireless market research firm Wireless Expertise, the number of smartphones sold worldwide each year is expected to increase from around 165 million in 2009 to 423 million in 2013, or about 28% to 30% of the total mobile market.

The study also indicated that the total number of smartphone users is expected to hit 1.6 billion, fuelled by a demand for mobile applications.

“With over four billion mobile users around the world compared to approximately one billion PCs, mobile will become the ideal channel for businesses to reach their consumers,” explained Anuj Khanna, CEO of Wireless Expertise.

Khanna also indicated that mobile operators have to adopt a dual app store strategy, using the store model in conjunction with a browser-based widget store, to “provide the greatest potential for a mass-market proposition”.