McLaren boss Ron Dennis stepped up his battle with Ferrari by accusing them of using an illegal car to win this year's Australian Grand Prix.
Dennis is furious that Ferrari persuaded motor racing's governing body, the FIA, to reconsider their decision not to punish McLaren for being in possession of confidential documents about the Italian team.
A court of appeal due to sit later this month could now dock McLaren points and Dennis has hit back by sending an open letter to FIA president Max Mosley, and Luigi Macaluso, president of the Italian Automobile Federation.
Dennis claims Ferrari's sacked technical manager Nigel Stepney told him there were two design elements of the Ferrari car he believed to be in breach of FIA regulations.
One, a rear-wing separator, was deemed legal, but the other, a 'flexi' floor, was proven to be illegal.
Dennis is adamant Ferrari ran their cars with the illegal floor at Melbourne, where Kimi Raikkonen won the race for the Italians.
In his letter, Dennis said, "Ferrari ran their cars with this illegal device at the Australian Grand Prix. McLaren chose not to protest the result even though it seems clear that Ferrari had an illegal advantage."
"Were it not for Mr Stepney drawing this illegal device to the attention of McLaren, and McLaren drawing it to the attention of the FIA, there is every reason to suppose Ferrari would have continued racing with an illegal car."