Interpublic, Octagon's parent company, has issued profit warnings and seen the value of its shares halved.

The company is now demanding a return on its �250m investment in British motor racing.

With several countries, including China, Turkey and Russia, in the hunt to take Britain's Formula One slot, Ecclestone's thinly-veiled warning will make uncomfortable reading for Silverstone chiefs.

"The world championship would carry on even if there were no British Grand Prix," said Ecclestone in The Guardian newspaper.

"We'd be sad to lose it, but if it came off the calendar there are lots of other countries waiting to take its place."

Ecclestone said he would not be prepared to promote the race "under the conditions Octagon has got".

Octagon's plans to carry out a string of improvements to the Silverstone circuit, including new sections of track and pit enclosures, have been postponed as the firm looks to cut costs.

"The problem is that the original idea was impossible to do," Ecclestone said.

"I always thought it would cost a lot more (than the planned �17m), but they said it wouldn't. [Now] they've got to scale down what's going on."