Sauber could be on the verge of being sold, according to the well-connected Swiss newspaper Blick.
"At the season opener an old rumour resurfaced," wrote veteran correspondent Roger Benoit. "Is Sauber being sold?"
Benoit said that, in the past, Peter Sauber usually categorically denied such rumours, but new boss Monisha Kaltenborn told Blick: "These rumours 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.