AUSTIN, Texas -- Red Bull team principal Christian Horner says he was "appalled" by a rival's accusations during Formula One's cost cap controversy after McLaren CEO Zak Brown said a breach of the cap would constitute cheating.
After analysing the accounts of all 10 teams, the FIA found Red Bull was the only one that had exceeded last year's budget cap.
Although figures have not been made public, the overspend is believed to be $1.8 million, while Red Bull states that the accounts it submitted in March were under the $145 million cap.
Red Bull claims the difference is partly due to clarifications that were made in June over what fell under the cap last year, while sources have indicated Red Bull also failed to claim a $1.4 million tax rebate, adding to its overspend.
The FIA is currently discussing the details of breach with Red Bull ahead of the next stage of the process, which will see the governing body present the team with an accepted breach agreement (ABA) whereby Red Bull will have the opportunity to accept a penalty dictated by the FIA.
If it rejects the penalty, the case will be submitted to the FIA's cost cap adjudication panel made up of independent legal and accounting experts for a ruling.
In the buildup to this weekend's United States Grand Prix, Brown wrote a letter to the FIA laying out his views on how a breach should be dealt with.
The letter did not mention Red Bull directly but said an overspend would "constitute cheating by offering a significant advantage across technical, sporting and financial regulations" before laying out a suggested penalty.
The letter enraged Horner, who made his feelings known in a news conference at the U.S. Grand Prix while sat directly next to Brown.
"Obviously Zak's letter, which wasn't copied to us but we've had sight of that letter, was tremendously disappointing," Horner said. "For a fellow competitor to be accused of cheating, to accuse you of fraudulent activity is shocking. It's absolutely shocking.
"Without the facts, without any knowledge of the details, to be making that kind of accusation. We've been on trial because of public accusations since [the race in] Singapore. The rhetoric of cheats, the rhetoric that we have had this enormous benefit, the numbers that have been put out in the media are miles off reality.
"The damage that that does the brand, to our partners, to the drivers, to our workforce, in an age where mental health is prevalent, we are seeing significant issues in our workforce. We are getting kids that are being bullied in playgrounds that are employees' children -- that is not right through fictitious allegations from other teams.
"You cannot go around just making that kind of allegation without any fact or substance. We are absolutely appalled at the behaviour of some of our competitors."
Given the chance to reply, Brown added: "My letter set out that if a team spends more than the cap they are going to get an advantage from the cap as with the technical rules in the sport.
"We are not taking a view over whether they did or didn't. My letter was 'if someone has' then here are the things that we think should be addressed.
"No different than if a ride height was incorrect or flexi wing or whatever the case may be. I didn't mention any teams, it was a general response now that we are into the cost cap era, so if someone breaches that here is what we think the ramifications are.
"I have no idea what the number is, I know none of the details, if we had more money to spend it would have put us in a better light in performance with more people and more upgrades whatever the case may be.
"We feel it will be a performance benefit and if someone has spent more than the allocated cost cap then that's up to the FIA to determine whether they have or haven't."
Horner also denied that his team's overspend had given Red Bull an advantage in last year's championship.
"Absolutely not," Horner said. "I think what you've got to look at is what are the relevant costs? And were the relevance costs within the cap and what's outside the cap. That's where the interpretation comes from and our view is that our relevant costs are within the cap.
"Obviously we are in discussions with the FIA about what those costs are and what are mitigating potential circumstances etc. So we had zero benefit from a development perspective or an operational perspective either for 2021 or for 2022 from the way that we operated within the cap.
"Our submission was significantly below the cap. We expected certain things to be potentially challenged or clarified as is the process in a brand-new set of regulations, but based on external, professional accounting third parties, interpretations of those rules of a 52-page document to police this were very clear from our side.
"So we absolutely and categorically don't feel that we've had any advantage either in 2021 or 2022, or '23 or '24 or some teams even talking about '26 -- it's totally fictitious."
Horner said the penalty system needed to be reviewed and clarified before next year because the wide range of sanctions had allowed Red Bull's rivals to campaign for the harshest penalties available for a minor breach without knowing the details of the case.
"The ranging suite of penalties are totally subjective," he added. "I think this is what's contributed to a concerted campaign for there to be a draconian penalty on Red Bull for what at the end of the day, we're talking probably, what is in contention with the FIA of a couple of hundred thousand dollars.
"I will say later why I think we have a different opinion within that submission of what our position was versus another. What has just been tremendously disappointing through this whole process has been the leakage that happened, suddenly we're tried and subjected to three weeks of effective abuse.
"Zak's got a very convenient memory of the letter he sent, accusing us of cheating and being fraudulent. It's just not right and it's got to stop."