World champion Sebastian Vettel has extended his contract with Red Bull by a further two years and will stay at the team until the end of 2014.

Red Bull are determined to keep hold of the German, 23, who they consider to be as good as anyone on the grid.
""Sebastian feels very comfortable within the team and the team feels very comfortable with him,"" team boss Christian Horner told BBC Sport.
""We started to talk about it earlier in the year and it came together quickly.""
Mercedes are known to be interested in signing Vettel in the future, and speculation had also linked him to a possible move to Ferrari.
Horner said he was keen to be able to head into the new season without the distraction of such speculation.
Fernando Alonso and Lewis Hamilton are both tied up for the long term and we're happy with what we've got
""We were keen to take away that distraction and concentrate on the racing.""
Horner said there were no break clauses or options in the contract, which is solid until the end of 2014.
""He's been with Red Bull since 1998, so it was a logical thing to do,"" he said.
""It was a straightforward and quick discussion.""
Vettel's team-mate Mark Webber has a contract only until the end of the 2011 season.
The Australian, 34, says he has not yet thought about his future beyond the end of this year.
Signing Vettel for such a long period means Red Bull are unlikely to be able to attract another top driver as most would be wary of joining a team that is seen to be so focused on Vettel.
Fernando Alonso's contract with Ferrari and Lewis Hamilton's with McLaren are both due to expire at the same time - at the end of 2012.
Horner said: ""He's so young so it makes sense to secure him for a sensible period of time.
""Fernando and Lewis are both tied up for the long term and we're happy with what we've got.""
Vettel clinched the championship at the last race of the season in 2010, when a strategic error by Ferrari left points leader Alonso stranded down the field.
The German romped to victory while Alonso could finish only seventh and the Red Bull driver leapfrogged the Spaniard to win the title by four points.
Vettel heads to the first race of the 2011 season, which is in Australia on 27 March, as favourite.
His Red Bull has looked the class of the field in pre-season testing, with Ferrari again its closest rival.
Vettel was not quoted on Red Bull's statement told Formula1.com: ""The winter period was pretty satisfying for us. We've managed to get good mileage under our belt - not as much as Ferrari - but more than we've ever done before.
""How good we are in the end compared to the others has a bigger question mark this season than any other season before.
""In previous years you had an idea of where you were and where the others were at the end of the test season, but this year it is almost impossible.
""There have been so-called experts coming forward offering their opinion but I don't think that anybody can realistically say what the pecking order will be in Melbourne, especially at the Albert Park track where we've seen surprises in the past.
""So let's wait and see. Within our team we are confident, so let's hope that we can stay that way.""
(Source: BBC)