The US Department of Justice (DoJ) acknowledged that it is investigating Google’s proposed settlement of $125m with authors and publishers, which, if settled, is expected to allow the company to continue with scanning millions of books into digital format.

The Justice Department said, in a letter, that it is reviewing concerns that the agreement could violate the Sherman Antitrust Act.

William Cavanaugh, a deputy assistant attorney general, said in the letter: “At this preliminary stage, the United States has reached no conclusions as to the merit of those concerns or more broadly what impact this settlement may have on competition.”

Google spokesman Gabriel Stricker reiterated the company’s previous statement saying: It’s important to note that this agreement is non-exclusive and if approved by the court stands to expand access to millions of books in the US.

The $125m deal was struck in October 2008 between Google and the Authors Guild and the Association of American Publishers. Google started scanning books in 2004 to make the content searchable online; the publishers and authors sued the company in 2005, alleging that it had violated copyright laws. Google settled the dispute through an agreement to pay $125m towards claims and establish a registry for publishers and authors to get paid if their titles are used online.

The Justice Department began its inquiry into the settlement after various parties complained that it would give Google a monopoly over the commercialisation of millions of orphan books.

Denny Chin, United States District Judge of the Southern District of New York in Manhattan, who is charged with reviewing the agreement, set a deadline of September 18 for the government to present its views. Judge Chin has also scheduled a hearing on the settlement for October 7.