FIA President Max Mosley, has today (Wednesday), written to the manufacturers that comprise the Grand Prix Manufacturers' Association, warning that despite claims that the threat of a breakaway is close to being settled, he is sticking with his original plan and that manufacturers must commit to the 2008 Formula One World Championship season by March 31, or face exclusion.

In the letter, which Pitpass has seen, Mosley writes:

"A Formula One team which does not enter before 31 March would nevertheless be able to submit an entry at a later date and such an entry might be accepted by the FIA subject to the relevant sporting regulations and provided the number of teams did not exceed twelve, including the late entry.

"However," he continues, "unless the FIA and the Competing Teams are persuaded that extenuating circumstances apply, even where such a late entry is accepted by the FIA prior to 30 June, late entering teams will not be invited to join in any discussions regarding the finalisation of the Sporting Regulations and entry will only be possible on the basis that the team accepts the Sporting Regulations as finally adopted and published prior to 30 June."

In the days leading up to the Bahrain Grand Prix, there was widespread speculation that the breakaway issue might be resolved, though this was never likely since the GPMA is awaiting the result of an EU investigation into the proposed purchase of F1 by CVC Capital Partners.

A meeting took place in Bahrain between the manufacturers and Bernie Ecclestone, but nothing was resolved, with McLaren boss insisting that the issue is not all about money, despite claims to the contrary in the media.

In recent weeks it has been very clear that Mosley and Ecclestone are adopting quite different approaches to the situation, with the FIA President seemingly opting for the 'bad cop' role, whilst the F1 supremo acts as 'good cop'.

With this latest letter, Mosley makes it clear that he has no intention of easing up the pressure on the manufacturers.