Williams driver Alex Wurz has confirmed he is quitting Formula 1 with immediate effect.

The Austrian, who returned to the cock-pit this year after a long spell testing, has struggled in comparison to his team-mate Nico Rosberg and rumours of his decision to hang up his helmet surfaced over the weekend in China.

Wurz has had a bad run in the last six events - and has not scored any points now since his fourth place finish at the race affected European Grand Prix back in July.

The 33-year-old, who made his Formula 1 debut with Benetton in 1997 and who finished on the podium in Canada in June, explained that he has started to doubt his own commitment.

"In such a hard fought environment as Formula 1, I have always maintained that if you have a moment's doubt about what you are doing, then it is time to stop," he said.

"Privately I began to have these thoughts earlier this year and so have decided that now is the time to make my announcement: I am retiring from active racing in Formula 1.

"I would like to thank my family and fans, everyone at AT&T Williams and my previous teams, as well as the media, for all of their support during my Formula 1 racing career.

"Racing this season has been a real pleasure, especially securing the podium in Canada which was pretty sweet along with a number of other strong races, but now it is time to call it a day. I'd like to thank the team for accepting my decision and I wish them all the best for the last race of the year."

Eurosport