The Web commerce giant says it will give customers tens of millions of dollars' worth of free Amazon Coins to spend on developers' apps on Kindle Fire from the tablet's Appstore when it launches the new currency in May.

The firm promises to make it "quick and easy" for customers to buy additional Amazon Coins using their Amazon accounts.

Amazon Appstore developers will earn their standard 70% revenue share when customers make purchases using Amazon Coins, whch are pegged to the US dollar, with one Coin equivalent to one US cent.

In June last year, Facebook ditched its Credits virtual currency platform in favour of a system which allows developers to be paid in a local currency of their choosing. Facebook said the the roll-out of Credits had slowed uptake of gaming applications, requiring users to switch in and out of multiple currency options - from US dollars, to Credits and back again to in-game currencies - and adding new layers of friction to the monetisation of developer applications.