The U.S. Justice Department is taking a closer look at Google's proposed $12.5 billion acquisition of mobile phone maker Motorola Mobility.
The extended review disclosed Wednesday had been widely expected since Google Inc. announced the Motorola deal last month.
Most of Google's big moves have been closely scrutinized by federal regulators because of the power it has gained as the Internet's search and advertising leader.
Google also makes Android, a leading software system for mobile phones. The advantages that Google has gained from Android may be one of the focal points of the Justice Department's inquiry.
Despite the increased government scrutiny, Google has won approval for all its acquisitions so far. Antitrust experts expect regulators to sign off on the Motorola deal too.