In the wake of unspecified claims that are understood to have been made against him by a female employee, parent company Red Bull in Austria has opened up an official probe into the matter.
A statement issued by it on Monday said: “After being made aware of certain recent allegations, the company launched an independent investigation.
"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."
It is understood that Horner will now meet with the independent legal representatives on Friday to discuss the matter.
Source: Autosport