Kubica signs as third driver at BMW Sauber

The Pole, who had his first F1 test with Renault earlier this month as a prize for his title success, will test regularly for the team and drive their third car in Friday practice at Grands Prix.

"It's a fantastic opportunity for me," said Kubica. "I'm going to prove that I have earned it. For a young driver like me the three-car rule is a godsend.

"In the past, test and replacement drivers were only sent out on test tracks, but I will get to know all 19 Grand Prix circuits and the ins and outs of a GP weekend. I would like to thank everybody who has helped me along the way over the last few years. Without these people I would not now be looking to a Formula One involvement."

BMW Motorsport director Mario Theissen added: "We have been following Robert's progress and are very impressed by his performance in recent years. He has worked hard to achieve his success without major support.

"We are convinced that he has the potential and the will to make the leap into Formula One and are delighted to be able to give him the opportunity to do so. As the number three driver he will gain experience while at the same time helping the team develop the car."

Kubica's deal comes after a host of established drivers were linked with the third driver role at BMW-Sauber, including Indy Racing League champion Dan Wheldon and McLaren tester Alexander Wurz.

It also means that the Pole, who finished runner-up in this year's Macau Grand Prix, will not do GP2 next year despite a recent test in the category.