German Formula One driver Sebastian Vettel is likely to switch to Red Bull Racing from smaller sister team Toro Rosso next year, according to Red Bull advisor Helmut Marko.

"I think so, yes," Autosport website (www.autosport.com) quoted the Austrian as saying.

"He's a special one and he is very developed for his age. He can be very aggressive in the car but he's also technical and well-trained.

"Red Bull has been with him for eight years and we have a contract for another couple of years," Marko added.

Toro Rosso are co-owned by Red Bull energy drink billionaire Dietrich Mateschitz but the Austrian said last month that he intended to sell the Italy-based team by 2010 because of rule changes.

Vettel last year became the youngest driver to score a point in a Formula One race when he finished eighth for BMW Sauber at the US Grand Prix while still only 19.

The German has failed to score a point in this season's opening three races but has still impressed in the Ferrari-powered Toro Rosso.

"For the next three years he has a contract with Red Bull, not Red Bull Racing," Toro Rosso co-owner Gerhard Berger told Autosport. "But I don't know where he'll be next year."

Red Bull's current drivers are Britain's David Coulthard, now the oldest driver in the sport at 37, and 31-year-old Australian Mark Webber.