The European Union antitrust chief, who has already charged Google with favoring its own shopping service in internet searches, said on Monday that she was now examining its deals with phone makers and operators.
The comments by European Competition Commissioner Margrethe Vestager follow a year-long investigation into Android, the world's most popular operating system for smartphones, triggered by two complaints.
A decision on the shopping service could come this year. Like the Android case, it could lead to a fine of up to $7.4 billion or 10 percent of Google's 2015 revenue, and force it to change its business practices.
Vestager said big companies should not try to protect themselves by holding back innovation.
"That's why we're looking closely at Google's contracts with phone makers and operators which use the Android operating system," she said at a conference organized by the Dutch competition authority.
"Our concern is that, by requiring phone makers and operators to pre-load a set of Google apps, rather than letting them decide for themselves which apps to load, Google might have cut off one of the main ways that new apps can reach customers."
The Commission said last year that it was also investigating whether Google had prevented smartphone and tablet manufacturers from developing and marketing modified and potentially competing versions of Android.
Another area of concern was whether Google had illegally hindered the development and market access of rival applications and services by bundling some of its applications and services distributed on Android devices with other Google products.