Sumner Redstone, chairman of CBS Corp. (CBS) and Viacom Inc. (VIA), provided no update Thursday on his negotiations with creditors or on the sale of movie theaters at his privately held firm, National Amusements Inc.

"National Amusements continues to make excellent progress and has an excellent working relationship with its creditors," said Redstone on a conference call with analysts following CBS' second-quarter earnings release.

"I will reserve further comment until we have something definitive to announce," he added.

National Amusements, the controlling shareholder of CBS and Viacom, is in the process of selling parts of its movie theater chain in order to meet a $500 million debt payment required by its lenders in October. The sale effort comes amid a sharp economic downturn and difficult financing environment.

-By Nat Worden, Dow Jones Newswires; (212) 416-2472; nat.worden@dowjones.com