The 65-year-old, who sold his Hinwil based outfit to BMW at the end of 2005, said he fears the Munich manufacturer's withdrawal from formula one could mean the closure of the team.
"I respect and accept the decision but am still finding it hard to digest," Sauber, who retains a 20 per cent shareholding of the team he founded in 1993, told the German news agency DPA.
It has been suggested that Sauber could now step back in and resume running the outfit as a privateer, but the Swiss played down that prospect.
"The position we are in now makes it very difficult," he said, without elaborating. (See related rumor)