Sao Paulo - Sebastian Vettel and his Ferrari team-mate Charles Leclerc defended their team Thursday, dismissing suggestions that the Italian outfit had done anything suspicious to generate extra engine power this year.

Speaking ahead of this weekend's Brazilian Grand Prix, four-time world champion Vettel declined to go into any detail, but made clear his feelings on "cheating" claims made by Red Bull's Max Verstappen in the wake of the United States Grand Prix two weeks ago.

"I don't think there is much to be said about it," said Vettel. "I think that comment was very immature... I ignore it because it is irrelevant. We want to answer on the circuit."

The German driver added that the Austin race was "not a good weekend for us" and said that "on top of the fact that we have a performing engine, we also have a car that I think is very efficient".

He added that if Ferrari did have a power advantage, it was a great achievement by the team's engine department because Mercedes had had an advantage for the last five years.

"For a couple of months, we are ahead," he said. "Hopefully, it stays like that for the next five years - and I don't care what people think or say."

He added, without naming Verstappen, that "if that's what he thinks, that's what he thinks... If next week, he thinks something different then, in the end, we don't care so much".

Vettel said his suspension failure in Austin was probably caused by the bumpy track while Leclerc said he felt no extra motivation to win this weekend after the speculation surrounding Ferrari's engines.

"I personally don't have any motivation to prove them wrong," he said of the team's critics. "I think we all know inside the team what we are doing and there's absolutely nothing wrong.

"And we are also confident that things will come back to normal here."

Leclerc is set to take a 10-place grid penalty for taking a new engine in Brazil.

"Obviously, it won't be easy with the penalty but I believe it was the best opportunity for us - for the rest of the championship.

"I will try to limit the damage as much as possible and then I'm sure we will see the advantage of changing the engine in Abu Dhabi."