Mercedes driver Lewis Hamilton revealed he had noticed Red Bull’s rear-wing flexing at high-speed during the Spanish Grand Prix weekend and suggested it could be worth up to three-tenths of a second in lap time.

Speaking to Sky Sports F1 after qualifying, the seven-time world champion commented: “The Red Bulls are really fast on the straights.

F1 2021 | Spanish GP 2021 Race Review | Hamilton vs Verstappen AGAIN!

“They have this bendy wing on the back of their car which they put on today and they gained at least three tenths from this wing.

“So they will be quicker down the straights than us and it will be hard to keep them behind, but that doesn’t mean it will be impossible.”

Teams including Red Bull have used aeroelasticity in the past to find straight-line speed gains but the FIA has stringent load tests that must be passed which detect any adverse rear flex on the wings.

Asked about Hamilton’s comments after Max Verstappen finished second to the Briton in Sunday’s race, Horner categorically denied that the team’s car features any component that breaks the rules.

Horner also insinuated that Hamilton had been told to bring up the so-called “bendy” wing by Mercedes.

“Of course the cars are scrutineered thoroughly and there's pull back tests, there's all kinds of different tests it has to pass,” Horner said.

“The FIA are completely happy with the car, that it has passed all of those tests that are pretty stringent.

“So I was surprised to see his comments on that but it's something that Toto has mentioned to me previously. I doubt it was Lewis's opinion, it probably came from elsewhere.”

Mercedes boss Toto Wolff was tight-lipped on the subject when asked for a response to Horner’s suggestion he had encouraged Hamilton to mention it.

"It’s good fun,” Wolff said. “We discussed it, but everybody’s…let me not comment.”