Infiniti Red Bull Racing team principal Christian Horner has stressed that it was Mark Webber's own decision to leave the team and Formula 1 racing at the conclusion of the season.
Webber, who has appeared to be at war with certain factions of the outfit in recent seasons as team-mate Sebastian Vettel swept to three consecutive World Drivers' Championships, will join Porsche's sportscar project in next year's World Endurance Championship.
The driver had told Australian media as recently as last week that he was in control of his own future, citing a strong relationship with Red Bull owner Dietrich Mateschitz.
Webber will continue to be a Red Bull-supported athlete despite walking out on the company's flagship F1 team.
In a team statement acknowledging Webber's impending exit, Horner thanked the 36-year-old for his six years of service to the squad, which he has helped to Constructors' Championship titles in each of the last three years.
“I am sure Mark thought long and hard before making what has no doubt been a very difficult decision,” said Horner, who it is understood was informed that the announcement was pending little shortly before it was released by the Porsche and Webber camps.
“His achievements in Formula 1 are extensive and I am sure he will continue to push hard and build on that record until the end of the season.
“We support Mark's decision, he has been an excellent addition to the team since joining us in 2007 and we wish him all the best in the next stage of his career.”
The statement also confirmed that “the decision on who will replace Webber will not be made until later in the season”.
The 2013 Formula 1 World Championship continues this weekend with the British Grand Prix, which has been won by Webber in two of the last three seasons.