The news comes about three weeks after a tattoo model and stripper announced she had a long-term affair with James while he was married. Several other women have since come forward to claim they, too, had sex with James during his five-year marriage to the best-actress Oscar winner.
Bullock reportedly has moved out of the home she shared with James and his three children from previous relationships.
"There is no sex tape," Bullock said in a statement to People.com Tuesday. "There never has been one and there never will be one."
Bullock's remarks were in response to an online report claiming James had the tape in his possession and planned to use it against her in a possible divorce case, People.com said.
The statement was the first the actress has personally made regarding the many salacious stories surrounding her marriage.
Attkisson leaves CBS News, reportedly over network's 'liberal bias'
Astronomers offer more expansive view of universe