Zak Brown has demanded a ‘very thorough investigation’ from the FIA after rule changes were made to outlaw a device on Red Bull’s car ahead of the United States Grand Prix.

The reigning world champions admitted to having a bib device in the RB20 cockpit that would allow them to change the ride height of their car in Parc Ferme conditions between qualifying and the race.

This would be illegal as per the FIA regulations, although there is no evidence of Red Bull using the component, and a spokesperson has denied as much. Brown, however, is less convinced and demanded greater transparency ahead of the race in Austin.

“Well, why would you design it to be inside the car when [with] the nine other teams, it is designed to be outside the car?” he said to Sky Sports F1. “And therefore, the rules… there are… you know, ingenuity is part of Formula One, and then there are black-and-white rules.

“You cannot touch your race car, other than things like driver comfort… they chose their words very carefully saying ‘When the car is fully assembled’, but you’re allowed to not have the car fully assembled in Parc Ferme and when you’re working on driver comfort.

“Also, what doesn’t quite stack up is the comment that you can’t modify it. Then why does the FIA feel that they need to put a seal on it? If it’s not accessible post or during Parc Ferme then why put a seal on it? So I’m very happy to see [that] the FIA is on it - I think it needs to be a very thorough investigation.

“Because if you touch your car from a performance standpoint after Parc Ferme or in Parc Ferme, that is a black-and-white, material, substantial breach which should come with massive consequences. Touching your car after Parc Ferme is highly illegal within the rules, so I think the FIA needs to get to the bottom of were they [or] weren’t they?

“Why would you design it to be inside the car when the nine other teams haven’t? So maybe unfair of me to say… of course, I have an opinion on whether I think they have or haven’t [used the component]. But you know, I think the FIA needs to be very diligent in their bottoming out whether they think they have or they haven’t.”

The McLaren Racing CEO later added: “I’d like some more answers before I’m prepared to kind of go ‘right, I guess they were or they weren’t’. But I think the FIA will bottom it out.”