"At the season opener an old rumor resurfaced," wrote veteran correspondent Roger Benoit. "Is Sauber being sold?"
Benoit said that, in the past, Peter Sauber usually categorically denied such rumors, but new boss Monisha Kaltenborn told Blick: "These rumors have always existed.
"If someone comes along who can strengthen us sportingly and commercially, we will make a decision in the interests of the team."
Founder Peter Sauber took back his Hinwil based team in the wake of BMW's F1 exit in 2009, subsequently giving part-ownership to Kaltenborn.