Sumner Redstone said he "no longer trusts" Viacom's board or Chief Executive Philippe Dauman to act in the media company's best interests, according to a spokesman for the 93-year-old mogul.
The comments from Redstone, the controlling shareholder of Viacom and CBS, are the latest in a spat with Viacom which will likely affect the direction of the company after Redstone dies or becomes incapacitated.
Last month, Redstone ejected Dauman and another director from the board of National Amusements Inc, which controls 80 percent of the voting shares of Viacom. Dauman filed a legal challenge to that maneuver and questioned Redstone's mental competence.
Redstone responded on Wednesday to a letter sent to him a day earlier by Fred Salerno, Viacom's lead independent director, who pleaded for a meeting with Redstone and warned of further court battles if he remained inaccessible to the board.