McLaren boss Zak Brown said the claim from Red Bull’s Helmut Marko that Lando Norris is not mentally strong enough to dethrone Max Verstappen was “inappropriate” and in “poor taste”.

Speaking ahead of this weekend’s US Grand Prix, Red Bull motorsport adviser Marko said Norris is “not the strongest mentally”.

Norris, 24, has opened up in the past about his mental health struggles, particularly in the formative years of his Formula One career.

“I read Helmut’s comments, which I felt were disappointing but not surprising,” said Brown.

“Lando has been an ambassador for mental health. It is a serious issue that he has brought to the forefront and to make it okay to talk about. To choose to poke at that situation is pretty inappropriate and it sets us back 10 or 20 years.

“It is all fun and games as to how some people go racing and the tactics they use but I thought that one was in pretty poor taste.”

Norris’ win at the last round in Singapore a month ago means he trails Verstappen by 52 points with 180 still to play for over the remaining six rounds.

Norris has taken 26 points out of Verstappen in the last four races. And there will be an additional eight points up for grabs in Austin with a sprint race on Saturday.

Norris has also been handed a possible championship boost after Red Bull were ordered by the FIA to make changes to their car.

Rival teams claimed Red Bull have been gaining an advantage by running a contentious device which allowed them to adjust the setup of the car between qualifying and the race – something which is not prohibited in the sport’s rules.

Red Bull have admitted the device exists but say they cannot access it when the car has been built.

“If you breach parc ferme rules that is a massive breach and there should be consequences if that has happened,” added Brown.

“We are asking questions as to whether it has been used in an inappropriate manner.

“It is up to the FIA as the regulator to get on top of it and come up with a solution that is transparent and satisfactory to all the teams because I am not alone with my concerns as to what we have seen and heard.”

Responding to Brown’s comments, Horner told Sky: “There has been a bit of moaning from one of our rivals.

“It is the FIA’s job to look into these things. It is on a list of open-source components that has been available for the last three years. The FIA are satisfied but (it is sealed) to satisfy a bit of paranoia elsewhere in the paddock.

“I feel sometimes it is to distract from what is going on in your own house. Sometimes you try and light a fire somewhere else. It is part of F1 and I am sure there will be other stuff that comes up between now and the final race in Abu Dhabi.”