The Belgian Grand Prix at Spa was dropped on Monday after teams decided not to attend the race because of new restrictions on tobacco advertising in Belgium.

The British and French Grands Prix are the only two operating without tobacco advertising.

And Stewart says Britain should not take its race for granted even though it has been run since F1's first season in 1950.

"Everyone is in love with Spa-Francorchamps, and particularly with Eau Rouge, but the bottom line is that it has had its Grand Prix taken away," Stewart told Motorsport News.

"For whatever reasons, they struggled to get their venue in order and if one of the most historical events can be taken away it is a warning for everyone else.

"If we still want an F1 race in Britain, we must fight for it."

Stewart is president of the British Racing Drivers Club, which owns the Silverstone circuit.

He has been an outspoken campaigner for greater state investment in British motorsport.

Most F1 teams are based in Britain and Stewart believes it would harm the motor industry as a whole if the Silverstone race was lost.

"It is not a given that we will have the British Grand Prix in the long term, so it is not a given that we will have a British motorsport industry," he said.

"If the British GP goes, the industry will not survive as we know it."

The British Grand Prix was threatened with cancellation by the International Automobile Federation (FIA) last year as a result of traffic chaos.

Given the competition from other countries to host races the threat was taken seriously, and promoters Octagon paid a $5m bond to guarantee improvements.

But F1 supremo Bernie Ecclestone still branded the British round a "country fair masquerading as a world event" after he had problems driving to the track on race day in July.