Mateschitz has been adamant for some time that, if Red Bull and Toro Rosso cannot be given a power unit that allows them to race at the front, then they will not remain in F1.

There had been an original deadline to find a solution of the end of October, but Mateschitz says that a final call has now been put back for a little while.

However, he concedes that there is now no chance of getting either the Mercedes or Ferrari power units that Red Bull wants.

Instead, its best solution appears to be a deal for Red Bull to run 'unbranded' Renault engines as a stop-gap for 2016, while Toro Rosso takes on board 2015 Ferrari power units.

Speaking to Red Bull's Speedweek website, Mateschitz said: "We have postponed our deadline by another two or three weeks.

"We cannot get access to a competitive engine anyhow. But it would be the first time we wouldn't have alternative ideas."

Rivals afraid

Mercedes and Ferrari have both been open about the drawbacks of supplying Red Bull with engines, in that it could risk them being beaten.

Mateschitz said it was clear that there was a competitive motivation behind what had happened.

"The works teams are afraid we would be faster than them," he explained. "That's clear for all to see."

No Renault buyout

With Red Bull appearing only to have a Renault option left, there have even been suggestions that the French car manufacturer could buy the team rather than Lotus.

But such a scenario has been dismissed by Mateschitz.

"Totally unthinkable," he said.