Sauber has left the Formula One Teams Association (FOTA), it has been confirmed.
The news follows the decision by Ferrari and Red Bull to also quit the body last week [see separate story - click here
"The Sauber F1 Team has declared its departure from the Formula One Teams' Association FOTA. We have explained the reasons for the decision to FOTA," the Swiss-based team said in a statement published by Reuters
No further explanation has been given, with the team adding that it preferred to keep its reasons private.
Meanwhile, Toro Rosso's position, Red Bull's sister team, which incidentally uses Ferrari engines, is also unknown.
Toro Rosso missed the FOTA meeting in London last week, but the squad has yet to officially confirm its position.
If Toro Rosso has also quit, FOTA will now be made up of just seven of the twelve teams, as HRT left in January.