The BMW Sauber team have released Sebastian Vettel to drive for Scuderia Toro Rosso, the German squad announced on Tuesday.
Twenty year-old Vettel was BMW's third driver and he had been linked with the Toro Rosso seat after comments from American Scott Speed that he would never drive for the Italian squad again following an altercation at the Nurburgring with team boss Franz Tost.
Speed, however, was in action during testing at Mugello last week, and Tost said there were no plans to replace Speed.
But BMW have announced they have released Vettel from his contract to drive for Toro Rosso, although the Italian squad are yet to announce their plans to the Hungarian Grand Prix.
"As our test and reserve driver Sebastian has carried out sterling work for us," said BMW boss Mario Theissen. "When he stood in for Robert Kubica in the USA Grand Prix he made history by becoming the youngest debutant to earn a world championship point.
"However, the current testing rules mean that he barely gets a chance to drive for us. Now he has been offered the opportunity to get inside a Toro Rosso cockpit. We have sponsored and coached Sebastian over a number of years.
"To place obstacles in his career path now would go against our concept of talent promotion."
He added: "BMW and Red Bull have a longstanding partnership in supporting Sebastian. Toro Rosso is the sister team of Red Bull Racing, and in that context it makes sense for us to release him for the testing.
"In a sponsoring partnership the main thing is to use the best opportunities that present themselves to a young driver at any given time."
German Timo Glock, the team's second tester, will take Vettel's role at BMW.