Google sets aside $500 million for advertising probe

The charge reduced the net income to $1.8 billion, or $5.51 per share for the first quarter, Google said in a filing with the U.S. Securities and Exchange Commission (SEC) late on Tuesday. The company reported net income of $2.3 billion, or $7.04 a share for the first quarter.

"In May 2011, 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 the filing.

However, Google said the charge will not have a material adverse effect on the company's business, even as it warned that it cannot predict the ultimate outcome of the Department of Justice's investigation.

Google did not provide any further details about the investigation in the filing. The company declined to comment on the investigation when contacted by Reuters.

The Internet search giant has had antitrust setbacks. It walked away from a search deal with Yahoo in 2008 when the Justice Department signaled it was prepared to challenge it.

There have also been a series of complaints made to regulators, many from Google rivals which specialize in vertical searches like price comparison websites, which are widely seen as a threat to Google's position as a key gateway to online information.

Several of these have complained to U.S. and European antitrust authorities that Google is seeking to hurt their business by making them hard to find in Google searches.