Red Bull Formula 1 team boss Christian Horner is under investigation after a complaint of inappropriate behaviour was made against him.

Red Bull said it took the allegations “extremely seriously” and has started an investigation.

Horner, 50, oversaw Red Bull’s record-breaking 2023 season in which the team won 21 of 22 races as Max Verstappen secured his third world title.

Horner says he “completely denies” the allegations.

Though Red Bull have not confirmed the nature of the complaint, BBC Sport understands the claims relate to an allegation of inappropriate behaviour of a controlling nature.

“After being made aware of certain recent allegations, the company launched an independent investigation,” Red Bull said in a statement.

“This process, which is already under way, is being carried out by an external specialist barrister. The company takes these matters extremely seriously and the investigation will be completed as soon as practically possible. It would not be appropriate to comment further at this time.”

Asked about the allegations by Dutch newspaper De Telegraaf, external, Horner said: “I completely deny these claims.”

Horner has been Red Bull team principal since they first started on the F1 grid in 2005 and has gone on to win seven drivers’ championships and six constructors’ championships with the team.

Having received an OBE in 2013, Briton Horner was appointed a CBE in the New Year’s Honours list last year after Red Bull won all but one of the grands prix in the 2023 season.

He raced competitively as a youngster but retired aged 25 and set his sights on managing an F1 team.

Horner married Spice Girl Geri Halliwell in Bedfordshire in 2015.

Red Bull are due to launch their latest car on 15 February before the new season which starts in Bahrain on 2 March.