Williams are keeping their options open after Spyker began arbitration proceedings against Formula One rivals Toro Rosso and Super Aguri over the legality of their cars.

"We are not involved at this time," a spokesman for the former champions said on Monday.

Williams have been supportive of Spyker's assertions that Honda-backed Super Aguri and Red Bull's Toro Rosso are breaking the rules by entering cars they have not designed themselves.

Both teams say their cars are legal.

A Spyker team spokeswoman confirmed arbitration proceedings had been put in motion.

However the Swiss-based Court of Arbitration for Sport (CAS) is likely to take some time to rule on the complex case that hinges on an interpretation of the confidential 'Concorde Agreement' between the teams, governing body and commercial rights holder.

Williams founder Frank Williams said last month that both Super Aguri and Ferrari-powered Toro Rosso should have their championship points and money withdrawn.