Ross Brawn has played down the likelihood that F1 teams will be allowed to field third cars in the near future.

The Mercedes GP team boss' former employer Ferrari has been running a high profile campaign for the rule change.

But Brawn told Bild newspaper: "I do not believe in three cars. Ferrari keeps the dream alive, but the starting grid is filled completely normally with at least 20 cars and there is no space for more."

Ferrari president Luca di Montezemolo insists the Maranello team would offer Michael Schumacher a full time cockpit if Fernando Alonso and Felipe Massa were allowed to have another teammate.

"We are not in a position to offer him a spot even if we would be in favour of having a third car on the track," the Italian said in a radio interview with La Politica nel Pallone on Monday.