Following unspecified allegations made against him by a female employee, Red Bull's parent company in Austria opened a formal investigation into the matter.
A statement issued on Monday said: “After becoming aware of some recent allegations, the company launched an independent investigation.
“This process, which is already underway, is being carried out by an external specialist lawyer.
“The company takes these matters seriously and the investigation will be completed as soon as practicable. It would not be appropriate to comment further at this time.”
It is understood that Horner will now meet independent legal representatives on Friday to discuss the matter.
Christian Horner, Team Principal, Red Bull Racing
Photography: Red Bull Content Pool
Horner, who continued his main duties with his team and attended the Formula 1 committee meeting in London on Monday, strongly denied any wrongdoing.
“I completely deny these allegations,” Horner told Dutch newspaper De Telegraaf.
The Red Bull Formula 1 team did not issue any comment on this matter.
The situation surrounding Horner comes ahead of an important period for Red Bull, as it completes its preparations for the 2024 Formula 1 season.
It is scheduled to launch its new car, the RB20, at its factory in Milton Keynes on February 15 – less than a week before the start of official testing for the new season in Bahrain.
Technical Director Adrian Newey revealed that the new design will be the “third evolution” of the original RB18 design from 2022 which has proven to be the most suitable car yet for Formula 1's new ground effect regulations.
Red Bull is coming off one of the most dominant seasons in Formula One history, winning 21 of 22 races to secure the Constructors' and Drivers' World Championships with Max Verstappen.
Horner has led the team since it entered Formula One in 2005, and is now the longest-serving team principal in Grand Prix racing.
His achievements in Formula 1 led to him being awarded a CBE in the recent New Year Honors List, for services to motor racing.
