Mobile phone developers are speculating that Google may be trying to damage the Windows Phone, following sharp drops in ad revenues for apps on the platform that make use of Googles AdMob ad network.

The chatter among developers was first reported by WMPU, which claimed that fill rates for ads on the Windows Phone using the AdMob network dropped from 99 per cent to as little as seven or eight per cent, with revenues similarly dropping by over 50 per cent.

The drop-off came shortly after Microsofts BUILD 2015 developer conference, where it announced several changes aimed at boosting the popularity of Windows Mobile, including making it easier for developers to port iOS and Android apps over to the new Windows 10 operating system.

While most developers have claimed that a bug, service change or unannounced API adjustment is likely responsibly for the drop-off, others believe Google may be intentionally sabotaging the rival platform.

The sharp declines in ad revenue will make it considerably harder for developers to monetise their apps on Windows Phones, and could lead to large-scale abandonment of the platform as developers decide it is not worth producing apps for.

Googles AdMob is one of the largest mobile ad platforms, enabling developers across all platforms to integrate an ad-serving SDK into their apps and earn money from the associated revenues.

“We are aware of reports of fill rate issues for Windows Phone developers in AdMob,” said a Google spokesperson in a statement to Business Insider. “Rest assured, we are actively investigating and working to fix this, and hope to have more details to share soon.”