SAN FRANCISCO  The Justice Department has begun an inquiry into the antitrust implications of Google’s settlement with authors and publishers over its Google Book Search service, two people briefed on the matter said Tuesday.

Lawyers for the Justice Department have been in conversations in recent weeks with various groups opposed to the settlement, including the Internet Archive and Consumer Watchdog. More recently, Justice Department lawyers notified the parties to the settlement, including Google, and representatives for the Association of American Publishers and the Authors Guild, that they were looking into various antitrust issues related to the far-reaching agreement.

The inquiry does not necessarily mean that the department will oppose the settlement, which is subject to a court review. But it suggests that some of the concerns raised by critics, who say the settlement would unfairly give Google an exclusive license to profit from millions of books, have resonated with the Justice Department.

A spokeswoman for the Justice Department was not immediately available to comment. A spokesman for Google declined to comment. Representatives for the Association of American Publishers and the Authors Guild could not immediately be reached.