Google today announced that it would set aside $500 million related to the possible resolution of a U.S. Justice Department investigation of its advertising business, resulting in lower first-quarter profit. "In connection with a potential resolution of an investigation by the United States Department of Justice into the use of Google advertising by certain advertisers, we accrued $500 million for the three month period ended March 31, 2011," Google said in a statement. "Although we cannot predict the ultimate outcome of this matter, we believe it will not have a material adverse effect on our business, consolidated financial position, results of operations, or cash flows," the company added.

As a result, the company has updated the affected financial data in its first quarter 2011 release.

The expense trimmed net income to $1.8 billion, in the period, Google said yesterday. The company had reported first-quarter profit of $2.3 billion on April 14.

Google faces an increasing array of scrutiny from regulators over its market leadership and handling of users' data. The Federal Trade Commission is preparing an investigation of Google's dominance of the search industry and has alerted technology companies that it plans to gather information for the probe.