Nokia was testing out the Android operating system on Lumia hardware before its smartphone and services business was purchased by Microsoft for $7.2bn.
The Finnish firm had successful ported Android to its Lumia handset range, sources told The New York Times.
It is not unusual for competing vendors to experiment with rival software behind closed doors. However, with Nokia's deal to use the Windows Phone operating system set to expire in 2014, this could have been a serious effort from the Finnish firm to potentially move away from the Microsoft OS.
Although moving to the Android operating system would not have required much tinkering in terms of engineering, it would have been a costly move for Nokia.
A switch would also have dealt a possibly fatal blow to Microsoft's aspirations in the mobile market, as Nokia has so far accounted for over 75 per cent of Windows Phone sales. Ultimately, this could have been a major factor in the Redmond-based firm's decision to acquire its partner.
Sales of Nokia's Lumia series have helped Windows Phone's global smartphone market share climb to 3.3 per cent, according to Gartner. This means it has overtaken BlackBerry for the first time, but Microsoft still has work to do as it still lags well behind Google's Android and Apple's iOS, which collectively make up 90 per cent of the market.
