The long-expected deal between Red Bull and Porsche for 2026 is under threat amid disagreements over control.

During the summer break, Formula 1 finally rubber-stamped its new power unit regulations to be introduced in four years time, with Audi wasting little time in announcing its entry at Spa.

Porsche was also believed to be waiting for F1 before confirming its tie-up with Red Bull.

The two companies even submitted documents to governmental anti-trust agencies revealing plans for the German manufacturer to buy 50% of the Technologies division that operates all Red Bull F1 operations.

However, it is now believed an internal dispute between Red Bull owner Dietrich Mateschitz and F1 chiefs Christian Horner and Helmut Marko is putting the deal at risk as they are unwilling to hand over decision-making control to Porsche.

"Red Bull has always been an independent team," Horner said via Sky Sports in Zandvoort.

"It's been one of our strengths, it's been the backbone of what we've achieved and our ability to move quickly. It's part of the DNA of who we are.

"We're not a corporately operated organisation, and that is one of our strengths in how we operate as a race team. That is an absolute prerequisite for the future.

"I think any relationship with any manufacturer or partners would have to fit with Red Bull," he added.

"We've got this new chapter, an exciting new chapter that we're heading into on the powertrain side of the business. We've got some phenomenal talent that has joined the company. We're in good shape.

"Time will tell whether we embrace a partner into that programme or, as the plan is at present, continue on our own."

As a result, Horner concluded, the ball is in Porsche's court if they still want to enter F1 with Red Bull under those terms.

"They need to decide whether they want to join that party or not," he stated. "It would have to be, as I say, within that culture of the way that we go racing."