Wurz picked up 13 points in his Williams-Toyota this season

The 33-year-old, who joined Williams as a test driver in January 2006, will miss the last race of the season in Brazil on 21 October.

"In such an environment as F1, I always maintained that if you have a moment's doubt about what you are doing then it is time to stop," said Wurz.

Williams will announce a replacement for the Austrian on Tuesday.

Alex is well-known, immensely popular and one of Formula One's gentlemen Sir Frank Williams

Wurz, who took over from Mark Webber this season, has picked up 13 points and lies 11th in the drivers' championship, two points behind team-mate Nico Rosberg.

He added: "Racing this season has been a real pleasure, especially securing the podium in Canada.

"That was pretty sweet, along with a number of other strong races, but now it is time to call it a day."

Wurz's F1 career began in 1997 with Benetton, before joining McLaren as a test driver in 2001.

He filled in for Juan Pablo Montoya in the 2005 San Marino Grand Prix and claimed a podium place, before joining Williams.

Wurz is reported to have made the decision after the Canadian Grand Prix in June, when he claimed a podium place behind Lewis Hamilton and Nick Heidfeld.

606: DEBATE What are your thoughts on Alex Wurz's decision?

He said he would like to work in F1 in the future, and may also race at Le Mans or other categories as well as working on improving road safety.

Williams team chief Sir Frank Williams said Wurz had provided an invaluable contribution to the team.

"Alex is well-known, immensely popular and widely regarded as one of Formula One's gentlemen," said Williams.

5live F1 correspondent's Maurice Hamilton added: "I think Alex has had his best days in F1 and he has probably made the right decision.