For the second time in less than three years, Google is under investigation by the US Federal Trade Commission (FTC) over antitrust concerns, Bloomberg reported Friday morning.

The inquiry will look into whether the company’s Android operating system has violated antitrust laws by privileging its own products and services over its competitors’ to an untenable degree, according to the Bloomberg report, which cited competing tech company executives who had complained about Google to the commission.

Both the FTC and Google declined to comment, the former saying that it does not comment “on an investigation or the existence of an investigation”.

Google has been the target of several recent complaints, many to do with its advertising networks – a business worth an estimated $5bn according to industry analyst Brian Weiser. A European company called Disconnect complained to the European Commission (EC) earlier this year that its app, which isolated search functions like Google’s from Google’s trackers, had been repeatedly thrown out of Google’s app store.

Others have voiced concerns to the FTC over the company’s YouTube Kids app, which they say unfairly exposes children to targeted advertising for unhealthy food, among others.

Google is currently under investigation by the European Commission, as well. European antitrust laws are less lenient that American rules, said NYU law professor Eleanor Fox, whose focus is trade regulation.

In an investigation into anticompetitive behavior, the FTC “would have to prove that [Google’s] conduct creates or increases market power”, said Fox. “In the EU, it’s a level playing field argument, and a competition on the merits argument. The US says that’s not enough. You have to go further and prove that prices will go up and that less will be produced.” With relationship to advertising, Fox said, those arguments are abstract and hard to make.

The FTC investigated Microsoft in 1993 over misuse of its market share through product bundling; that investigation closed but the Department of Justice then sued the company in 1998 over the same concerns, specifically its promotion of its own Internet Explorer over Netscape Navigator.

More recently, the FTC voted 5-0 in early 2013 to cease investigating the company (citing lack of evidence), but not until Google had agreed to change business practices including restricting access to advertising platforms that compete with the company’s own.