The success of Top Gear is built around the friendly competition between its three presenters.

But yesterday that rivalry was threatening to affect the future of the programme after two of them failed to sign new contracts amid a pay battle.

James May and Richard 'Hamster' Hammond are said to be demanding salaries more in line with that of co-host Jeremy Clarkson.

Pay dispute: Richard Hammond (middle) and James May (right) have reportedly refused to sign a contract with the BBC

He is believed to be paid almost £2million a year by the BBC while the other two earn more like £350,000.

They feel they should be better rewarded for helping to turn the show from a niche programme for car fanatics into a family-friendly ratings hit on Sunday night for BBC2, attracting audiences of more than 6million.

The BBC's failure to tie the two down to a new contract, with the current deal finishing at the end of the month, has led to fears in some quarters that they could quit.

Hammond: Crash made him a household name

Both men are currently in a stand-off with BBC paymasters after they 'turned down flat' the corporation's initial offer, saying it should be closer to Clarkson's.

There have been rumours for months that both May and Hammond have become tired of playing second fiddle to 48-year- old Clarkson, who has just struck a deal to promote the show's 'brand' around the world.

As part of a new agreement, on top of his wages for the UK show, he will also be paid to market the show for BBC Worldwide.

The deal gives him a healthy cut of profits from the show, which has 235million viewers around the globe.

His bumper award has given Hammond and May more resolve to win a significantly better deal for themselves.

The current series ends this month and the next is due to begin some time in the winter.

Hammond, 38, has become much more of a household name since he nearly died following his high speed crash at 288mph during filming for the show in September 2006.

May, 45, has also raised his profile having appeared in the successful BBC2 show Oz and James's Big Wine Adventure, with Oz Clarke.

A source close to the negotiations said: 'Internally there is talk that there might be a chance for the first time that there could be a break-up of the team, it has got that bad.

'There has been a lot of pulling out of hair, a Mexican stand-off. For the first time it is possible that one or both might leave.'

The insider added: 'They don't want to accept second status any more.'

But another source close to the programme insisted: 'No one is bigger than Clarkson. They should be happy for what they get. It is really a case of being the bass player in the Rolling Stones or the lead singer in a band that no one has heard of. I think they will sign.'

G & T at the wheel: Clarkson in the Arctic scene which led to a rocket

It has been suggested that the BBC has told the pair that it is in fact they who benefit from the show's popularity as it is their 'power base' for popularity.

The BBC is said to have argued that without Top Gear the pair's wider media exposure would be damaged.

James May is understood have strongly denied suggestions he is refusing to sign the contract, claiming he is not bothered what Clarkson is paid.

His agent yesterday said: 'We are not looking for parity with Jeremy but the best deal for James. But that is never going to be what the BBC first offer.'

She said they had only just started contract negotiations with the BBC, but said it was normal for these discussions to take 'quite a bit of time to reach agreement'.

Hammond's agent had nothing to say while the BBC declared: 'We never comment on contract negotiations.'

This week, Top Gear was censured by the BBC's governing body for glamorising drink-driving after Clarkson and May were seen drinking gin and tonic at the wheel of a truck in the Arctic Circle.

The programme was described as 'grossly irresponsible'.