Renault will have to compete without their "mass damper" system

Renault's hopes of stemming Ferrari's advance in the title battle have been dealt a blow after an innovative design on their car was ruled illegal.

The court of appeal of Formula One's governing body, the FIA, said on Wednesday that the team's "mass damper" contravened the sport's rules.

Renault will now have to race in the remaining five Grands Prix of the season without the system.

Renault's Fernando Alonso leads Michael Schumacher of Ferrari by 10 points.

The issue went to the court of appeal after the FIA objected to the decision of its own race stewards at last month's German Grand Prix to deem the system legal, even though the FIA's technical department had outlawed it.

Alonso has said he believes Renault can win in Turkey

The FIA views the "mass damper" - a counterweight mounted within the nose of the car - as a movable aerodynamic device, even though it never comes into contact with the airflow around the car.

This is because it makes the car more stable, and allows the aerodynamics to work more efficiently.

Alonso had a trying race in Germany, the first time Renault had raced without the system since last year, and could finish only fifth as Schumacher won.

Renault admitted that not being able to use the "mass damper" had harmed their performance, but said they were confident they could overcome the problem.

And they were encouraged by their performance the following weekend in Hungary, when Alonso dominated and was on course to win until he was forced into retirement by a loose wheel nut.

Renault were one of six teams running a "mass damper", but they were hurt more than the others by its banning because they had pioneered it and designed their 2006 car around it.

HOW THE LEAD WAS CUT Canada, 25 June: Alonso 25 points ahead of Schumacher USA, 2 July: Alonso 19 points ahead France, 16 July: Alonso 17 points ahead Germany, 30 July: Alonso 11 points ahead Hungary, 6 August: Alonso 10 points ahead

Other teams had simply added it on after they discovered Renault's system, and had not made it work as effectively.

Speaking before the hearing, Renault engineering director Pat Symonds said many other aspects of the F1 rules would be thrown into doubt if the FIA won the case.

"I really do not believe the FIA can win the appeal on the grounds they have said," Symonds said, "but if they do then we really have to start to relook at the definition of what a racing car is - its suspension, everything.

"If the FIA choose to interpret in the particular manner they are doing now, then there are many, many other parts on the car open to interpretation.