Renault have become the fifth team to announce they will not race in Formula One next season unless plans for the controversial budget cap are scrapped. Ferrari yesterday confirmed their intention to pull out of the championship joining Red Bull, Toro Rosso and Toyota in the boycott.

They are angered by Max Mosley's proposal which would see teams who adhere to the £40million budget cap given greater tehnical freedom than those who do not.

Mosley, president of motor sport's world governing body, the FIA, now faces showdown talks with all the teams at a Heathrow airport hotel on Friday if they are to save the sport.

Renault president Bernard Rey said: “We remain committed to the sport, however we cannot be involved in a championship operating with different sets of rules, and if such rules are put into effect, we will be forced to pull out at the end of this season.”

The budget changes were ratified at a meeting of the World Motor Sport Council two weeks ago but Mosley is now under growing pressure to back down.

Renault team boss Flavio Briatore said: “Our aim is to reduce costs while maintaining the high standards that make Formula One one of the most prestigious brands on the market. We want to achieve this in a co-ordinated manner with the regulatory and commercial bodies, and we refuse to accept unilateral governance handed out by the FIA.

“If the decisions by the World Council are not revised, we have no choice but to withdraw from the world championship at the end of 2009.”

Before Renault joined the boycott, Bernie Ecclestone said he was hopeful of brokering a peace deal between the teams.

“I hope common sense will prevail because the last thing we want to do is lose any of the manufacturers or teams in Formula One,” he said. “Formula One is Ferrari and Ferrari is Formula One. It's not going to change.”

The deadline to enter the series is
29 May and only three teams, Brawn GP, Force India and Williams, are thought to be willing to fall within the budget cap.

Up until now, however, Mosley has been adamant that the cap will go ahead as it stands, even insisting F1 could live without Ferrari, who are the oldest team in the sport.