Verstappen was questioned on the matter on Friday in Bahrain, after beating Ferrari’s Charles Leclerc to pole – a day after an anonymous email with a link to messages purporting to involve Horner was sent to Formula 1 personnel and media.
A drive of messages was on a link in the email, which was sent to 149 people involved in the sport, mainly senior figures and permanently accredited media.
After the messages emerged, Horner said in a statement: “I won’t comment on anonymous speculation. But, to reiterate, I have always denied the allegations.”
F1 president Stefano Domenicali and FIA president Mohammed Ben Sulayem met on Friday in Bahrain to discuss the matter.
Verstappen was first asked whether he was confident Horner remained the right person to lead Red Bull Racing.
He said: “From my side, and I think what I can see also from the mechanics and the engineers, we are fully focused on the car and the performance here during the weekend.
“And that’s how it should be, I think, and that’s what we continue to do, because it’s not our business. We’re not particularly involved in that.
“And we are here, we are paid to do our job, and that’s what we are doing and that’s also what we love doing. So that’s what we focus on.”
Asked to clarify whether he had full faith in Horner’s leadership, the 26-year-old said: “Listen, when I look at how Christian operates within the team, he has been an incredible team boss. So absolutely, from the performance side of things, you can’t even question that. So that’s what I’m also dealing with.
“I speak to Christian a lot, and also throughout the weekend here. He’s fully committed to the team. He’s also here for the performance. Of course probably a little bit distracted. But like I said before, we just focus on the performance side of things and that’s how we all work together.”
The Horner controversy has overshadowed the first race of the new F1 season.
Red Bull announced on Wednesday, on the eve of first practice, that following an internal investigation into the allegations, conducted by an external barrister, the grievance against the 50-year-old had been “dismissed”.
The statement, issued by Red Bull’s head office in Austria, did not offer further information, saying the company wanted to protect the privacy of those involved.
On Thursday, the cache of photos of messages was sent in the middle of second practice.
And on Friday the matter continued to dominate conversation in the paddock.
Ben Sulayem was seen to give Horner a hug at the circuit and, before qualifying, posted a photograph on his Instagram page taken at the inauguration of the Bahrain track in 2004. It featured Ben Sulayem sitting next to Prince Andrew,, external with the caption: “Bahrain GP memories”.
On the track, Verstappen – a strong favourite for a fourth consecutive world championship – took pole position as expected.