The first row of Formula One's most anticipated season in decades erupted in Bahrain today as a number of teams raised doubts over the legality of the new McLaren MP4-25 car.

Renault and Red Bull have cried foul over the design of the car, claiming a slot on the rear wing illegally reduces drag and increases straight-line speed. The McLaren design channels air through the cockpit and will allow Jenson Button and Lewis Hamilton, their drivers, to control the flow and affect the performance of the car's rear wing and its speed on straight runs.

Charlie Whiting, the FIA's technical chief, has seen the design and approved it on the final scrutiny check before Sunday's Bahrain Grand Prix, but Bob Bell, the team principal of Renault, warned that the development could spark an "arms race" between the teams at a time when everyone has been working hard to cut costs.

"It is fundamentally clear that the McLaren wing design is totally illegal," Bell said. "They have driven a cart and horse through the spirit of the rules and regulations.

"They have opened up another arms race and it's going to cost everybody a lot of money. The governing body needs to be a lot stronger with these things. I think that it is ridiculous in this era where we are all trying to save money. We are restricted by the number of people that we can bring to the track, with mechanics working ridiculous hours at night to prepare the car.

"Now we have just opened another arms race that will cost us all a lot of money. It's just a nonsense. I think the governing body needs to be more responsible in decisions like this."

Moving bodywork is banned in the regulations, but drivers are not considered to be a part of the car so if they use their legs to vary the air flow through their car it is not deemed to be illegal. Last year, Brawn GP sparked a similar row when they began the season with a double diffuser on their cars, which it was claimed helped to improve downforce and speed.

Christian Horner, Red Bull's team principal, said he was considering a protest over the design. "It is not as big an issue as the 'double diffuser' was last year, but it is a similar kind of thing," Horner said. "I am not sure yet if we are likely to protest. I would say that is unlikely and that we will look at it and develop our own variant of the same idea."