Hiring by tech companies under DOJ investigation

The focus of the investigation is not clear, but appears to address the possible agreements among these companies not to poach top executives from one another. The investigation includes biotech company Genentech, as well as other tech companies the Post said, citing two unidentified sources.

The reported move by the DOJ reflects plans for a more aggressive approach to antitrust enforcement by the administration of U.S. President Barack Obama.

Christine Varney, assistant attorney general in charge of the DOJ's Antitrust Division, said last month that as part of an overall plan to get tougher on antitrust concerns, the DOJ should take a close look at the high-tech and Internet industries and new ways of measuring antitrust activity there.

A number of tech companies including Google have been under scrutiny in the U.S. for possible antitrust behavior. The Federal Trade Commission is said to be investigating whether the close ties between Apple's and Google's boards of directors violate antitrust laws. Google's deal with authors and publishers on scanning of books has also attracted government scrutiny in the U.S.

The DOJ could not be reached for comment.