There are more than 20,000 apps available in Android Marketplace - the app store for mobile phones running Google's Android OS, says Androlib.

The Android-dedicated website said it had been tracking apps since the store launched, as Google won't release the data itself.

Androidlib said 62.2 percent of the apps were free of charge and the store saw the most apps published during November this year, when 350 apps a day were being made available on Android Market.

However, rival Apple is thought to have around 100,000 apps in its iTunes app store.

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See also: Android vs iPhone vs BlackBerry: the best OS for apps?