Melbourne, Australia  - The next round in the fight over aerodynamics among the Formula One teams is to take place after the Australian and Malaysian grand prix.

Motorsport's ruling body FIA said Saturday that it set a hearing before its appeal board for April 14 in Paris

Ferrari, Renault and Red Bull are protesting a decision Thursday by three race commissioners at the Grand Prix in Melbourne to allow Brawn GP, Williams and Toyota to field new diffusers, a part of the car that improves its aerodynamic performance. The protesting teams said the new diffusers give their rivals an unfair advantage and break racing regulations.

The appeal was lodged by the national racing associations in Italy (Ferrari), France (Renault) and Austria (Red Bull).

The dispute centres around the rear diffusers, a part of the bodywork between the rear wheels and under the rear wing that disperses air from under the car.

It is claimed the designs of the Brawn GP, Williams and Toyota cars would give them a speed advantage of up to 0.5 seconds a lap as a result of the extra downforce that boosts a cars grip on the track.

New regulations limit the size of the diffusers, but the three teams have found a potential loophole in the rules by designing the rear bodywork to effectively act as part of the diffuser, increasing its size.

Their cars placed high in the first three training runs ahead of Sunday's first race of the season. Williams' Nico Rosberg turned in the best times in all three practice sessions Friday and Saturday.

Jenson Button and Rubens Barrichello with Brawn GP are considered the favourites going into the grand prix in Melbourne and Sepang, Malaysia, on April 5. dpa