LONDON (Reuters) - Red Bull team principal Christian Horner has had his contract extended ahead of a season in which the Formula One champions will chase a fourth successive title.

A team spokeswoman said the 39-year-old Briton had agreed a multi-year extension.

Horner has been at the helm of Red Bull since the Austrian energy drink company entered the sport in 2005 after taking over the Jaguar team.

Red Bull and Germany's Sebastian Vettel, the youngest triple world champion at the age of 25, have won both titles for the past three years.

The Milton-Keynes based team are due to unveil their 2013 car at the factory on Sunday before testing starts at the Jerez circuit in Spain on Tuesday.

(Reporting by Alan Baldwin, Editing by Clare Fallon)