The European Union is “advancing” with its investigation into the practices of Google, including the search giant’s Android efforts, according to The Wall Street Journal, although it is not clear when its investigation will be completed.

Citing comments from competition chief Margrethe Vestager, it was suggested that more formal proceedings could be opened against the US company. The European authorities began looking into Google last year, with investigations into its advertising efforts launched separately from the mobile probe.

The Android investigation was described as a “high priority”, but no deadline appears to be in place.

The regulator is looking at whether Google had restricted the market for apps and services by “requiring or incentivising” device makers to support its own products. Also in the spotlight was whether Google had looked to limit the penetration of Android-based alternative platforms.

While alternative versions of Android have been developed, notably Cyanogen, this has not been adopted by top-tier Android device makers, and has instead been used by smaller players and boutique mobile device brands.

Google has already been on the losing end of a similar action in Russia, brought by rival Yandex – a search engine which saw its dominance reduced as users shifted to mobile and Android, where Google was the default.

Late last year, it was reported that the US Federal Trade Commission was also looking into Google’s Android activities, on similar grounds.