Google and book publisher and authors have improved their class-action settlement but not enough to avoid antitrust troubles, the U.S. Department of Justice said in a filing and news release this afternoon.

The key quote in the filing:

"Although the United States believes the parties have approached this effort in good faith and the amended settlement agreement is more circumscribed in its sweep than the original proposed settlement, the amended settlement agreement suffers from the same core problem as the original agreement: it is an attempt to use the class action mechanism to implement forward-looking business arrangements that go far beyond the dispute before the court in this litigation."

The Justice Department liked changes that removed Google's "most favored nation" status but said the settlement as revised would still give the search company an unfair advantage.

It said in the release that "the amended settlement agreement still confers significant and possibly anticompetitive advantages on Google as a single entity, thereby enabling the company to be the only competitor in the digital marketplace with the rights to distribute and otherwise exploit a vast array of works in multiple formats."

Today's filing sets the stage for a Feb. 18 hearing before a federal judge considering whether to approve the agreement, which was originally reached in 2005 after a fight over Google's efforts to digitize the world's books.

Other critics of the agreement have lined up in recent months, giving the judge plenty to consider.