Fresh doubts have been cast over the future of the British Formula One Grand Prix after the operator of Donington Park failed in a bid to raise £135m to fund the venue's redevelopment.

The motor racing circuit near Kegworth, Leicestershire, was due to undergo a major £100m revamp in preparation for the event, which is set to be staged at Donington Park for 10 years from 2010. However, the plans - which include rebuilding and relocating the paddock and pit complex to allow for a three-mile extension of the race track, designed by Formula One circuit architect, Hermann Tilke - have been hit by planning delays and financial issues.

Donington Ventures Leisure Limited's (DVLL) confirmed that it had not been able to secure the £135m necessary to help fund redevelopment proposals, which now means it has also missed a deadline to prove it had not breached a contract with Formula One rights holder Bernie Ecclestone. A DVLL spokesperson said: "Despite higher than expected levels of interest and very positive early indications, the bond - which was launched with Citi Group last week - has failed to secure enough subscription ahead of today's deadline."

"The news dealt an unexpected blow to staff and management at the circuit, who still have a deadline of 12pm on Monday 26 October to remedy a breach of contract with Formula One rights holder Bernie Ecclestone, in order to keep any plans for retaining the existing 17-year Formula One contract alive." According to the BBC, Ecclestone said that plans for the British Grand Prix to remain at Silverstone in Northamptonshire should Donington Park be unable to host the event are not yet guaranteed.

Ecclestone told the BBC: "We are not going to do special rates for Britain. If they [Silverstone] can't make it work then don't do it. If that happens, there won't be a British Grand Prix. Simple as that."