Google Inc has received formal notice from the U.S. Justice Department that antitrust investigators are looking into its settlement with publishers that would help make millions of books available online.

Asked if the company had received the civil equivalent of a subpoena, Google Chief Legal Officer David Drummond told reporters: Yeah, we did.

The Justice Department's antitrust division has also sent formal information requests to Lagardere's Hachette Book Group and another publisher, the Wall Street Journal reported on Tuesday.

Under a proposed settlement last October between Google and the Authors Guild and the Association of American Publishers, Google agreed to pay $125 million to create a Book Rights Registry, where authors and publishers can register works and receive compensation from institutional subscriptions or book sales.

Google's plan is to let readers to search millions of copyrighted books online, browse passages and purchase copies.

Drummond said he expected the federal court assessing the settlement and the Justice Department to work parallel to each other.

It's a separate question from the approval of the class action settlement, Drummond said. The judge's job is not to review every question that the Department of Justice might think about.

He also acknowledged the possibility that the agreement might be tweaked, if necessary. We're open to that sort of thing ... if it's a compelling argument. We haven't heard it, he said.

Two experts on digitization told Reuters in April that the Justice Department was making inquiries about the settlement. U.S. states attorneys general have also made inquiries, an expert told Reuters.

Google is also part of a Justice Department probe into possible pacts by big tech businesses not to poach one another's talent.

Google, Yahoo and Microsoft, computer and music player maker Apple and biotech company Genentech, now owned by Roche Holding AG, have received notices that the Justice Department has a formal probe under way, according to the source, who declined to be identified because the investigation is ongoing.

The U.S. Federal Trade Commission, which also has antitrust responsibilities, has a probe into Google and Apple Inc's overlapping board members.

The Justice Department probes are evidence that its antitrust division under new chief Christine Varney will be more aggressive than President George W. Bush's antitrust team.

In a speech last month laying out her antitrust philosophy, Varney pledged a more aggressive approach to dealing with dominant companies that use their market power to crush competition and lamented a lack of recent scrutiny of mergers by companies in the same supply chain.

(Reporting by Diane Bartz; Editing by Tim Dobbyn and Brian Moss)