Christian Horner has claimed that rival F1 teams contacted Red Bull sponsors, amid their cost cap controversy last season.
Red Bull were found to be in breach of the $145 million cap after they overspent by $1.8 million in four main areas.
The team was subsequently fined $7 million and received further restrictions on its aerodynamic testing allowance, on top of the restrictions for finishing the Constructors' Championship in first in 2022.
Horner claims rival teams used "underhand" tactics to court Red Bull's sponsors, suggesting that they could bring the brands into disrepute.
"It tainted us. These things get used by your rivals," he told the i newspaper.
"We had one of them contacting our sponsors and partners making suggestions that we would be bringing their brands into disrepute. That was just underhand."
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Horner: You can guarantee other teams will be scheming
Much has been said about whether Red Bull could win every race in 2023, after dominating the opening races of the season.
However, Horner says he does not expect Red Bull to go unchallenged this year, citing that there will always a be a team "scheming" in the background attempting to slow them down.
"There is always something, always a technical directive that drops, a game changer," said Horner.
"You can guarantee that the others will be scheming, 'how can we slow them down?'
"It's part of the game. Having lived through it before you become more seasoned in how to ride it out."
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