The FCC is turning up the heat on Cablevision and Fox to resolve the retransmission dispute that has knocked Fox’s Gotham and Philadelphia stations off of Cablevision systems for the past seven days.

William Lake, chief of the FCC’s media bureau, sent a letter Friday to Cablevision prexy and CEO James Dolan and News Corp. chief operating officer Chase Carey asking them to justify by Monday the moves that each side has made in the long-running retrans wrangle. Lake’s letter asks the toppers to explain how the sides have been negotiating in “good faith,” as called for in the law governing retransmission consent deals between subscription TV providers and broadcasters. Lake’s letter follows a statement from FCC Julius Genachowski earlier this week that criticized both companies for “spending more time attacking each other through ads and lobbyists” than negotiating. Cablevision and Fox execs have not held face-to-face negotiations since Monday, though the sides have had brief telephone conversations.

“We ask each of you to describe to us how your company is satisfying this important statutory obligation in the context of your retransmission consent negotiations,” Lake wrote. “In particular, we request that you describe with specificity what has transpired since you initially began your negotiations, and detail the efforts your company is making to end the current impasse. If you are aware of any conduct by the other side that you believe violates the good faith requirement, please so indicate and provide supporting evidence. Please submit this information to me by the close of business Monday, October 25, 2010.”

Lake further asserted that the shutoff of Fox’s WNYW and WWOR New York and WTXF Philadelphia for Cablevision’s 3 million subscribers “affects millions of innocent consumers who expect to watch their preferred broadcast programming without interruption. We urge you to place the interests of these consumers first and conclude your negotiations promptly.”

Fox said it would respond to the FCC by Monday but had not further comment.

In a statement, Cablevision’s Charles Schueler, exec veep of communications said: “We welcome the FCC’s intervention. Whether through FCC action, binding arbitration or any other means, the time has come for News Corp to end the Fox blackout of 3 million Cablevision households.”