Under-fire Horner very important to Red Bull's success, says reigning champion Verstappen

An investigation into the conduct of Formula One's longest serving principal, and husband of former Spice Girls singer Geri Halliwell, was announced this month after allegations by a female employee.

Horner has denied the undisclosed allegations and has continued to carry out his regular duties, including appearing at the team's car launch and a news conference during pre-season testing.

"I think he’s very important, otherwise he wouldn’t be in that position for such a long time," Verstappen told reporters at the Sakhir circuit when asked how the situation might affect his title chances.

"Let’s say if your team boss disappears for whatever reason for one or two races, not much is going to happen, because everyone is in their role and they know what they have to do in the short term.

"But it’s all about people management over time. And then of course things will start to be different, if one of the leaders starts to not be there any more.

"But we are not thinking like that...we just trust the process that we are in as a team of course, to see what the outcome will be."

Verstappen said he and the team, who won 21 of 22 races last season, were focused on performance and excited to start the season.

The Dutch driver is chasing his fourth successive championship.

Horner was due to return to the Gulf kingdom on Wednesday, with a decision from Red Bull Austria expected imminently although the British-based team have no control over the process.