While Bernie Ecclestone trumpeted that the 'majority' of F1 teams had signed up to a new edition of the Concorde Agreement, thee were several notable absentees from his list.

Although the sport's current 'big-hitters' - Red Bull, Ferrari and McLaren - are all understood to have reached verbal agreement with Ecclestone, both Williams and Mercedes have not, and remain on the sidelines along with the three newest teams in the field, Caterham, Marussia and HRT. Ecclestone made his announcement during the build-up to qualifying at the Malaysian Grand Prix, amid various rumours of a possible F1 stock floatation and suggestions that certain teams may have been offered inducements to sign up.

Reports, which first appeared on the Sky News website during last weekend's Australian GP before being pulled by the broadcaster, claimed that both Ferrari and Red Bull - which defected from teams association FOTA late in 2011 - had been offered preferential financial terms and potential seats on the board of F1's holding company. Britain's Daily Telegraph has since revealed that cash bonuses are also being offered to teams who had won the constructors' title since 2000, those that had not changed their name since 2000 and an annual 'double champions' payment for teams who had won titles 'in any two or more consecutive seasons including or after the 2008 season'.

While Williams has a proud F1 history, it has not featured as strongly in recent years, and would be unlikely to qualify for bonuses. The same is true of Mercedes, and the German marque is thought to be particularly incensed with the lack of equality in the deals on offer. The only mass manufacturer left on the grid following Renault's withdrawal, has already threatened to take the matter further, even hinting at legal action, and also holds the card of its own exit, which would potentially affect not only the entry list, but also the plans of engine customers such as McLaren and Force India.

The Three-Pointed Star has declined to comment on the situation, but could go as far as legal action under EU competition law, with respect to restriction of competition and abuse of a dominant position. The F1 giant would still be in a better position than the likes of Marussia and HRT, however, as the sliding payment scale would leave the third-year teams without a penny. Fellow newcomer Caterham, however, has finished tenth in the past two season, earning itself some financial reward.