The US Department of Justice late on Friday asked a judge to encourage negotiations on a sweeping deal that would put Google at the centre of the world of information in out-of-print books.

The regulator’s filing in US District Court in New York formally objected to elements of the proposed settlement on antitrust and other grounds. But it said “the public interest would best be served by direction from the court encouraging the continuation of those discussions ... the United States does not want the opportunity or momentum to be lost”.