"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," F1 supremo Ecclestone was quoted as saying in Britain's Sunday Express newspaper.
Donington is due to replace Silverstone as the venue for the British Grand Prix in 2010 and circuit operators have promised to invest 100 million pounds ($165.6 million) on revamping the circuit over a five-year period.
"I'm hoping Donington... do all the things they must do. And if they can't, we will come back to Silverstone," said Ecclestone.
Silverstone has hosted the British Grand Prix since 1987. From next season it will host the MotoGP which is to switch from the Donington circuit.