British Formula One Grand Prix promoters say they are doing everything they can to secure the future of the race by improving conditions and access to Silverstone for spectators.

Octagon Motorsports announced on Thursday that they would invest �4m in the Northamptonshire circuit before this year's race in July.

Octagon vice-chairman Murray Smith said: "We're doing everything we have to do in order to retain the Grand Prix."

Octagon Motorsports worldwide has a 15-year deal to promote the race.

Crowds Expected

Mr Smith said: "Everybody knows we're doing what we've been asked so it would surprise me a great deal if we lost it."

After a history of traffic problems, Octagon was only allowed to go ahead with the race last year after posting a �5m guarantee and restricting attendance to 60,000.

Octagon said that there would be no limit on spectators this year and, with ticket prices remaining static or even going down, they hope for bumper crowd in excess of 100,000 on 20 July.

Improvements will include a new road from the main entrance to the paddock, new debris fencing, and refurbished toilets and public areas.

The investment in Silverstone is part of a �7.5m package to improve all five British racetracks run by Octagon.