IT is "impossible" for Max Mosley to survive as head of world motorsport, according to long-time adversary Sir Jackie Stewart.

There is increasing pressure on FIA president Mosley to quit over lurid Sunday newspaper allegations about his private life.

Three-time Formula One world champion Stewart, who has already demanded Mosley's resignation, claims the sport's big backers met at yesterday's Spanish Grand Prix to discuss the issue.

"He's gone beyond anything they would tolerate," the Scot told BBC Radio Five Live.

Stewart said Mosley's behaviour would have contravened the companies' "corporate moral guidelines" and that motor clubs around the world, which also come under the auspices of the FIA, would not approve either.

"Therefore it's very difficult to see how he could stay under these circumstances," added Stewart.

Mosley faces a vote of confidence on his future at an extraordinary meeting of the governing body's general assembly in Paris on June 3.