Red Bull advisor Helmut Marko says confirmation of their engine plans post-2021 should come in the new year.

Back in October, Formula 1 was shaken by the news that Honda, who only returned to the sport in 2015, would pull out at the end of next year, leaving both Red Bull teams in a tricky predicament.

That's because, under the current regulations, former partner Renault would be the automatic supplier if a solution wasn't found.

However, since then, it has been confirmed that continuing with the Honda power unit but taking production in-house has been Red Bull's preferred option as it allows the team to remain independent from the other manufacturers.

And now Marko has revealed a final arrangement is close.

"This is a difficult topic but I would say we are 85-90% close to a deal," he told Red Bull-owned Servus TV.

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"Honda is helping us a lot so that Red Bull can continue to work with their power unit with technical assistance. But we need to freeze the developments as this is the most expensive part and we cannot afford that.

"Otherwise, everything looks good and we may able to complete the deal soon," he added. "I expect to be able to provide more clarity about 2022 in the coming weeks and sign a deal in the new year."

A key element, as Marko alluded to, in continuing with their current engine has been the demand for a development freeze, as Red Bull are unwilling to take on the additional costs.

But despite initial opposition from Renault and Ferrari, a compromise does seem likely.

“Everything is on the right track,” the Austrian said. “The talks with the FIA and Liberty are advanced. We hope a corresponding decision will be reached this year.

“It is clear that not all manufacturers agree, but I believe an agreement is on the horizon. From the perspective of common sense, it makes sense not to accept immense development costs with an immensely complex engine if you know this engine will only be used for a reasonable amount of time.”

After Honda's decision to leave, attention has also turned to the next generation engines which could be brought forward to 2025 from 2026.

And for the first time, Red Bull has now suggested that if the regulations are favourable, they could continue making their own power units.

“If the hints become true that the new engine is much simpler in design; that the MGU-H is eliminated, and that it remains innovative but the annual cost limit is somewhere around $50m, then it’s no longer such a complex issue as the current engine,” Marko told Motorsport.com.

“That means you could then do the development for such an engine with the paraphernalia we will have in Milton Keynes.”

Confirming if that meant taking engine supply in-house, he replied: “Correct. Whether on its own or in cooperation, that’s a matter of negotiation then, I would say.”