Formula 1 supremo Bernie Ecclestone has warned the owners of Donington Park that the venue has until the end of September to prove funding is in place to host the British Grand Prix in 2010, or lose the race altogether.
Following warnings from Silverstone last week that it can only remain on standby for so long, Ecclestone has demanded a guarantee that Donington can continue with its planned necessary upgrades in time for next year's race.
"They have got until the end of September to produce a bank guarantee and their contract depends on that. If they don't, it's adios amigos," he told the Sunday Express at Valencia.
"I'm hoping Donington... do all the things they must do. And if they can't, we will come back to Silverstone."
A Donington spokesperson told AUTOSPORT last week that the circuit was "100% confident" of its ability to host next year's British GP.
"All of the plans for this will be delivered on time, will be revealed when we are ready to do so, and tickets will not go on sale to the public until after that point.
"We have already stated the need to defer the race until 2011 and have also made it clear that the original debenture scheme had to be put on hold in spring this year as a result of the global recession.
"However, new plans are currently being finalised and details will be announced as soon as we are ready to discuss them publicly."
Donington Park recently appointed Jayne McGivern's Red Grouse Properties group to oversee the redevelopment, and rejected Silverstone's offer to host the race next year so that it can take more time to get plans in place.
A Donington Park spokesperson also dismissed Silverstone's warnings that time was running out: "The comments coming from Silverstone are, of course, unsurprising given the circuit management's desire to mount a bid for an F1 return on track.
"We have no need or desire to engage in a public rivalry or dispute with Silverstone and we will not allow any comments, no matter how public or scathing, to deflect our attention from the most important jobs at hand."