Formula One boss Bernie Ecclestone is worried Renault may pull out of the sport following accusations the team ordered a crash to help Fernando Alonso win a race.
Renault's departure would be a blow to a sport that lost Honda after last year's championship and is set to lose BMW at the end of this season.
F1's governing body is investigating "alleged incidents," believed to be a crash by Nelson Piquet Jr. that allowed teammate Alonso to take advantage of an early pit stop and win last year's Singapore Grand Prix.
Ecclestone said Renault team principal Flavio Briatore told him he knows of no such conspiracy.
Piquet Jr. crashed on the 13th lap, and Alonso's gamble to run a short 12-lap strategy before pitting paid off as the Spanish driver went on to an unlikely victory.
"This is not the sort of thing we need at the moment," Ecclestone said in The Times of London on Tuesday. "Them leaving the sport is a danger, obviously. I mean, I hope that it isn't like that, but it's the sort of thing that might happen.
"All I know is that Flavio is insisting that he knows nothing about it. I think the FIA are looking into everything."
Piquet Jr. was fired by Renault last month after a season and a half. The Brazilian driver complained about unequal treatment by Briatore compared to his two-time world champion teammate.
Ecclestone suggested that Piquet Jr.'s F1 career could be over.
"You can safely say that he's sort of in trouble now," Ecclestone said. "You'd have to wonder what next, wouldn't you?"