FIA president Max Mosley says that Formula One must implement drastic cost-cuts by 2010.
Mosley told BBC Sport that the global credit crunch has intensified problems for Formula One and several of the smaller teams were now in danger of having to quit the sport.
"It has become apparent, long before the current difficulties, that Formula One was unsustainable," said Mosley. "It really is a very serious situation. If we can't get this done for 2010, we will be in serious difficulty.
"At the moment we've got 20 cars," said Mosley. "If we lost two teams, we'd have 16. (If we lost) three teams (we'd have) 14. It then would cease to be a credible grid."
Mosley is set for talks with the Formula One Teams Association over proposed measures to cut F1 team costs in half by 2010. If no agreement was reached, the FIA said, it would enforce its own measures.
