Berger (right) believes Vettel will thrive at Toro Rosso

The move follows the team's decision to take 20-year-old as a replacement American Scott Speed, who was sacked after the European Grand Prix.

Vettel has been released from his role as a test driver for BMW Sauber.

He became the youngest driver to score a Formula One point when he replaced the injured Robert Kubica to finish eighth in the US Grand Prix in June.

Toro Rosso said on Tuesday that Vettel would replace Speed, who was axed after the European Grand Prix.

The team's co-owner Gerhard Berger played down reports that Speed had been sacked after an angry row with Toro Rosso chief Franz Tost after the race in Germany.

606: DEBATE I hope Toro Rosso sign Bourdais and Vettel for 2008 as they are both have real talent FF

"I don't want to spend one more second talking about Scott Speed," he said.

"That's history. He didn't perform and that's why he isn't here any more."

But he admitted: "Lately we didn't have a good atmosphere and I don't want to say it's all Scott's fault, or our fault.

"But it just didn't work out and the only way is to stop it."

His comments were echoed by Tost, who said: "It has nothing to do with what happened there (the European Grand Prix).

"It was done before because we weren't happy with his performance. His progress wasn't in the way we expected."