Formula 1 supremo Bernie Ecclestone has warned Mercedes that it should think 'very carefully' about not supplying engines to Red Bull if needed.
The future of Red Bull's current engine partner Renault remains uncertain, as it closes in on a decision about whether or not to buy the Lotus team to create a new works outfit.
Renault is expected to make a final call on that matter by the end of this month, and once its long-term situation is clear it can then finalise what it will do for 2016.
Although it is adamant that it will see out its engine contracts with Red Bull and Toro Rosso, any change in its 'works' status with the energy drink giant's teams could change the situation.
And if Red Bull ends its relationship with Renault, that could open the door to a Mercedes engine deal if it can convince the German car manufacturer to go ahead with the plan.
Mercedes insiders suggest that the company remains divided about exactly what it should do if the door is open for a Red Bull deal.
While the team can see the performance and commercial benefits of a tie-up with Red Bull, equally giving the once dominant outfit a power boost could hurt the fortunes of its own works Mercedes team.
Speaking at the Belgian GP on Friday about Mercedes' position on supplying Red Bull, Ecclestone said: "They would rather not, I think….but they ought to think carefully about not giving one."
When asked what he believed would happen if Mercedes' refusal left Red Bull without engines, Ecclestone cheekily suggested: "Maybe someone will complain to the European Commission."