The prospect of the fragile accord surviving were put in doubt on Thursday - just 24 hours after being agreed - when Mr Mosley dispatched an angry letter to Ferrari president Luca di Montezemolo.

Mr Mosley demanded a public apology after Di Montezemolo hailed the departure of the 'dictator' after 16 years in office.

Di Montezemolo chose to respond privately, telling Mr Mosley he had been misunderstood and pledged to respect Wednesday's agreement that saw the FIA's planned voluntary budget cap scrapped to win back the eight rebel teams.

'Di Montezemolo replied yesterday,' Ferrari spokesman Luca Colajanni told reporters on Friday. 'It's pointless to go on with the polemic - it can only damage the sport.'

In a letter on Friday to the FIA's ruling council, Mr Mosley explained the deal with Fota and said that 'no doubt we face a difficult period.'

Mr Mosley dropped the contentious 40 million-pound (S$97.5 million) voluntary budget cap, instead agreeing to an unquantified - and unenforceable - instruction to reduce costs to the levels of the 1990s.

He insisted he wasn't bullied into submission by the eight rebel teams - including Ferrari and McLaren - but accepted that it is an uneasy truce.

'This may well result in short-term problems in Formula One,' Mr Mosley said. 'It is possible Fota will set up an independent series. That is their right, provided they do so under the International Sporting Code, but the Formula One world championship will continue to be run by the FIA as it has been for 60 years.

'The championship has had difficult times in the past, and no doubt will again in the future. But that is no reason to hand control to an outside body, still less one with little or no understanding of sporting ethics and under the control of an industry we have to constantly monitor.' -- AP