Red Bull have insisted that Sebastian Vettel's gearbox problem in the Brazilian Grand Prix was genuine and not a ruse concocted to allow Mark Webber to win the race.

Webber's victory at Interlagos buoyed him after a tough year and lifted the Australian to third in the drivers' championship.

It came after Vettel slowed from the lead with a gearbox issue - but eyebrows were raised as the champion's car kept going and maintained a fairly competitive pace behind Webber, still finishing second.

Team boss Christian Horner said this should be taken as a sign that Red Bull managed the problem well rather than evidence of deception.

"Categorically anyone that listened to the conversation between the race engineers, or looked at the back of the garage at the amount of activity that was going on over that gearbox, would see it was genuine," said Horner.

"Of course there will always be people who have theories, but categorically there was an issue and that gearbox, how on earth it got to the end of the race is beyond me."

Vettel also insisted that his issues had been real and he had not slowed voluntarily.

"You can believe me, if I had the choice, I would have gone for the racing option," he said.

Horner denied that Webber's demeanour on the podium was too low-key for a winner and that this was another hint of something untoward.

"If Mark's slightly muted, I guess it's because he would've loved to have beaten Sebastian in a fair straight fight," said Horner.

"If anybody thinks that was concocted in any way, I can absolutely hand on heart guarantee you that based on the blood pressure on the pit wall, you can rest assured it was a genuine, genuine issue."

Webber refused to comment on the conspiracy suggestions, saying he had just focused on his own race.

"Well, I didn't drive Seb's car," he said.

"All I can do is what I can do."

Rival teams played down the suggestions of a contrived result, with Ferrari's Stefano Domenicali pointing out that with team orders now fully legal, Red Bull had no need to create a charade when they could have openly ordered Vettel to hand Webber first place.

"This year the regulation is pretty clear - you can say what you want to on the radio, even that Mark has to win the race!" said Domenicali.

"I cannot speak about the others because I do not know, I have to rely on what they are saying.

"At the end of the day it doesn't count because they were the fastest and they did a good race."