Mercedes-Benz has admitted that increasing its customer roster is a strong possibility for the 2010 Formula One season, although it would not reveal which outfits were on its shopping list.

The German marque is already the most prolific supplier on the F1 grid, providing both Force India and 2009 season pacesetter Brawn GP with engines, as well as its own 'works' team McLaren, but Motorsport vice-president Norbert Haug told reporters at the German Grand Prix that the company had the potential to increase its roster next season.

"We can get some refinancing from supplying three other teams [as well as McLaren] and this is the current plan, so we are in negotiations," Haug was quoted as saying by Reuters, "We could have three customer teams, that's the plan."

While this year's deal with Brawn had to receive special approval from the rest of the grid - agreement that was forthcoming as the field rallied around to keep the former Honda team on the entry list - the regulation limiting any one manufacturer to two customer teams is set to be rewritten in favour of doubling that number, paving the way for Mercedes to look at adding a third client to its output.

McLaren is understood to have the right to veto any proposed deal that Mercedes might consider, but approved a five-year supply deal to Force India which includes heavy involvement from Woking on other technical areas. While the Brawn deal remains a special case, Haug has admitted that he would hope to see the relationship continuing for years to come, even though the Brackley-based operation has put McLaren in the shade so far in 2009.

With the three newcomers expected on next season's F1 grid all apparently bound to using Cosworth engines, any expansion to Mercedes' customer base would have to come from within the current field, but Haug would not be drawn on speculation that Red Bull Racing was considering swapping its race-winning Renault powerplant for a supply of the German units.

"I cannot mention any team names," he said, "but the positive thing is that we get quite a few requests. Our engine is seen to be a strong one, probably the best one."