Christian Horner has hinted that Red Bull Racing's engine supply deal with Renault for 2010 is not set in stone, conceding that a switch to Mercedes-Benz customer powerplants is not altogether out of the question.

It has been rumoured within the Formula 1 paddock of late that the energy drinks-backed outfit – which, courtesy of Sebastian Vettel, secured its breakthrough victory in the top flight at its 74th attempt in the Chinese Grand Prix in Shanghai earlier this month – may be eyeing a move to Mercedes power next season, with the Stuttgart marque producing one of the most coveted engines in the pit-lane.

Horner stoked the flames of the fire during a press conference in Bahrain last weekend when he alluded to the 'quite good engine' the team currently receives from former world champions Renault, with the Englishman's words hardly a resounding vote of confidence in Red Bull's relationship with the Régie.

RBR's Renault contract expires at the end of the current season, and though Horner insisted the Milton Keynes-based squad is happy with the deal for the time being – with the French manufacturer having been allowed over the winter months to regain the ground it had lost on its rivals as a result of the cost-cutting engine freeze – he nonetheless reflected that Mercedes' KERS (Kinetic Energy Recovery Systems) technology is equally a potent selling-point.

“For the moment it is my belief that Dietrich Mateschitz (Red Bull owner) does not intend to negotiate with a new engine partner,” RBR's team principal told German publication Sport Bild. “Fortunately we have time, though. In these times, who knows what engine manufacturers are still going to be there in 2010?

“Ross Brawn has proved that it is possible to have a very good car even with a very new engine partner. In this case Mercedes is attractive, not only because of the engine. [Its KERS device] seems to be the best system in the field. It's compact and has no negative effect on the car balance, which is really the fundamental problem of other makers' KERS technology.”

Mercedes currently provides engines to three of F1's ten teams, in the shape of McLaren, current pace-setters Brawn GP and traditional tail-enders Force India.