BT has backed Google in its competition battle with Brussels over the tech's smartphone operating system Android, in an intervention that signals the nervousness of mobile operators after watching the power of Apple.

It is reportedly understood that Britain's biggest mobile operator BT, after its takeover of EE, has written to the European Commission rejecting anti-trust it has associated with Google. Google was charged with monopoly abuse over android last year formally. Watchdogs say Google was suffocating competition in the market for mobile web browsers and search tools by requiring handset manufacturers and operators to pre-install its apps.

Those who do not are barred from installing the main Android App store, Google play, a must kept according to competition commissioner Margareth Vestager. The regulator further claimed that Google's anti-fragmentation agreements are a threat to competition in the operating system market.

They are designed to prevent smartphone manufacturers from adopting the Android software code to create a new fork that may not be compatible with Google apps. BT's letter ultimately rejected both the charges against Android. The company had been prompted to intervene a bit on Google's behalf, in part by fears that the action by EU could possibly weaken Android would have an advantage to Apple.

The iPhone already accounts for a good amount of share of mobile operator profits as users tend to sign up for more valuable contracts and use up more data. Apple is able to extract favorable terms from operators who cannot afford to be cut off from supplies of its smartphone.

Google has meanwhile attacked the EU's investigation for failing to consider the iPhone as near competition to Android. Back in November, Google's legal chief said The Commission's case is based on the idea that Android doesn't compete with Apple's iOS. Google doesn't see it that way.