US federal regulators have begun a formal antitrust investigation into Google's business practices.

In a blog post Friday, the Internet search giant said it received notification from the Federal Trade Commission of the review on Thursday.

But the inquiry is expected to focus in large part on whether Google abuses its dominance of Internet search to extend its influence into other lucrative online markets, such as mapping, comparison shopping and travel.

Google maintains that most of the accusations of anti-competitive behavior come not from users, but from competitors.

Professor Jonathan Askin, Brooklyn Law School, said, "I think Google are going to raise some strong arguments on why it's very convenient and pro-consumer to have Google function and control the entire ecosystem in some form or another. I think it's going to be incumbent on Google to demonstrate why these functional separations are sufficient and why structural full divestiture sorts remedies are not."