As first revealed byautosport.com, Williams and Spyker have been threatening legal action over plans by Toro Rosso to race with a modified version of this year's Red Bull RB3, and plans by Super Aguri to enter cars based on last year's Honda RA106.

At the heart of the debate between the teams is the question whether the current regulations require each team to build their own cars from scratch, or are the rules simply preventing the sale of chassis and parts from one team to another.

FIA president Max Mosley has held the view that teams could make acquisitions from a third party contractor, which could supply more than one team.

Speaking about the situation last year, Mosley explained: "If the parts are designed and manufactured by another company, and you own the intellectual property rights of the car that requires them, then it is completely legitimate.

"The thing you can't do is if you're Williams you can't run a McLaren front wing. But both Williams and McLaren could run a Lola front wing."

However, Williams insists this is not permitted by the regulations or agreed on in the existing Concorde Agreement, which expires at the end of the year, the Briton placing an emphasis on the actual construction of a car by each team.

"I am adamantly opposed to chassis sharing, and we at Williams do not believe it is legal under the current rules," the veteran team owner toldthe Guardian.

"We are what you might call a traditionalist racing team, which believes that we are out there competing for two world championships - one for the best driver in the world, and one for the constructor who builds the best car in the world.

"As far as I'm concerned, it is absolutely in the regulations in black and white that every team must make its own chassis."

Williams and Spyker are said to be preparing an arbitration request with the International Chamber of Commerce in Switzerland, which they would launch if either Toro Rosso or Super Aguri are allowed to start the season with customer cars, come the Australian Grand Prix on March 18th.

Toro Rosso co-owner Gerhard Berger has already made it clear that his team will continue with their plans and shrugged off any threat of legal action by Williams or others.

"Williams or the other competitors are not the people who tell the FIA the rules," he toldautosport.com. "At the end of the day, the FIA or a judge has to do it.

"We made the decision a long time ago that we go this route, and we checked very carefully with different legal people, with an open view about everything.

"We got always a similar answer: that the way the regulation is written, how the Concorde Agreement is written, it should fit in perfectly with what we are doing."

Williams has also made it clear that new regulations permitting chassis sharing from 2008 should not be taken for granted - with the likes of Prodrive saying they plan to buy chassis when they enter the sport next year.

"In the presently issued rules for 2008, customer cars are not yet a done deal," Williams told the newspaper.