The agency, which opposes the $565 million merger for antitrust reasons, has asked for an expedited ruling, The Wall Street Journal reported Wednesday.

In August, a U.S. district judge rejected the FTC's claim that a merger of the companies would stifle competition and raise prices. A federal court subsequently refused the FTC's request to keep the companies from closing their deal pending an appeal.

Earlier this month, Whole Foods asked the appellate court to dismiss the case because the acquisition was completed. Whole Foods of Austin, Texas, closed its acquisition of Wild Oats of Boulder, Colo., in August. Together, the companies own more than 250 stores and have annual revenue of more than $6.5 billion.

In its motion filed Monday, the FTC said an appeal was still warranted because Whole Foods operates many of the Wild Oats stores separately for now.

An appellate court could stop the companies from continuing to combine certain operations, pending a full review of the merger in a separate administrative court proceeding, the Journal said.