Red Bull Racing's parent company Red Bull GmbH announced on February 5 that Horner was under investigation following an accusation made against him by a female colleague.

Horner emphatically denied the claim and the 50-year-old – who arrived in Bahrain on Wednesday ahead of this weekend's opening race of the season – has been cleared of wrongdoing.

Red Bull GmbH said it was confident the investigation had been "fair, rigorous and impartial", but added that the report – understood to stretch to 150 pages – is "confidential".

Mercedes boss Toto Wolff had called for the investigation to be conducted with transparency but no details of the allegations against Horner were reported.

Horner has made no public comment. The complainant also has a right to appeal against the verdict.

A statement from Red Bull GmbH read: "The independent investigation into the allegations made against Mr Horner is complete and Red Bull can confirm that the grievance has been dismissed.

"The complainant has a right of appeal. Red Bull is confident that the investigation has been fair, rigorous and impartial.

"The investigation report is confidential and contains the private information of the parties and third parties who assisted in the investigation, and therefore we will not be commenting further out of respect for all concerned. Red Bull will continue striving to meet the highest workplace standards."

Horner, who has protested his innocence throughout, was questioned by a lawyer for eight hours earlier this month at a secret London location.

During the internal probe, he continued to be present for official Red Bull activities – including a car launch in Milton Keynes earlier this month, where he insisted it was "business as usual", and pre-season testing in Bahrain last week.

Horner flew back to England as he awaited his fate before heading back to the Gulf kingdom on a private jet on Wednesday.

Horner has been Red Bull team principal since they entered F1 19 years ago and is the longest-serving boss on the grid.

He has overseen seven drivers' world championships and six constructors' titles.

Red Bull have dominated the sport in recent seasons and last year won 21 of the 22 races with Dutch driver Max Verstappen setting a new record for 10 consecutive victories as he wrapped up his third title.

Horner, who is married to former Spice Girls singer Geri Halliwell, was awarded a CBE for his services to motorsport in the New Year Honours.