"It's the first time I've heard about (that)," said the motor sport director and would-be Sauber team principal.
"We will discuss our strategy in June."
Theissen denied widespread Paddock speculation that BMW and Frank Williams' outfit will split as soon as next year.
He added: "We are talking to Sauber primarily on engine supply ... and I don't know what the outcome will be at the moment." -GMM