The new rules will be introduced for the 2004 season and are part of a major cost-cutting drive introduced by Mosley in F1.

Some top teams have claimed that the changes will not achieve what he wants.

But Mosley said that they were needed to stop some of the smaller teams going out of business.

The ruling effectively bans the use of high-revving engines just for qualifying - drivers will be demoted 10 places on the grid if they have to use a second engine during a race weekend.

"The idea that you fit three different engines in a weekend is massively uneconomic," Mosley said.

"It is terribly wasteful at a time when several of the teams have not got enough money.

"We can have some idealised view of things and say it nice to let everybody do what they want and spend as much money as they want.

"But when we start losing two, three or four teams off the back of the grid suddenly the whole of F1 is under threat.

"If you are the governing body one of your tasks is to try and foresee this possibility and deal with it.

'Holes in budgets'

"It is all very well for the top teams to say: 'If you save me $20-30m a year I will simply spend it on something else'.

"They have got the money and we are not concerned with that.

"The people we are concerned with are the people who are missing $20-30m out of their budget and absolutely no way of filling the hole.

"If you are spending, which some teams are, as much as $20-30m more than you have got you cannot do it for very long.