Lewis Hamilton has expressed his opposition to the idea of his Mercedes team supplying Red Bull with engines in the future.
Red Bull are pushing to use Mercedes engines having lost confidence in their current supplier Renault.
Asked if supplying Red Bull was a good idea, Hamilton said: "If we are serious about winning the world championship, probably not.
"Red Bull are a great team, but it's like giving Ferrari our engines."
Hamilton added: "We don't really need it. There is no financial benefit. We are good where we are."
Red Bull have a contract with Renault, with whom they won four consecutive drivers' and constructors' title doubles from 2010-13, until the end of 2016 but want to use Mercedes engines from next year.
Renault has been left behind by Mercedes and Ferrari since the introduction of complex turbo hybrid engines into F1 in 2014.
The French car company is considering its future in the sport having come to the conclusion that its relationship with Red Bull is not working from a marketing perspective.
It is in the late stages of talks aimed at taking back control of the Lotus team and again becoming an entrant in its own right - Renault owned the team from 2001-2009 and won two world title doubles with Fernando Alonso in 2005-6.
Insiders say Red Bull have sent Renault a legal letter giving notice of termination of contract on the grounds that the French company has failed to meet performance clauses in its contract.
Red Bull team principal Christian Horner refused to comment on that development, referring to it as "paddock gossip".
He said: "We have an agreement with Renault until the end of 2016 and anything other than [that] is purely speculation at the moment."
Asked if he was trying to get a Mercedes engine as soon as possible, Horner added: "Our aim is to be as competitive as we can as quickly as we can. First of all, we want to understand what the situation with Renault is and what commitment they have to making sure they are competitive."
Mercedes are wary of supplying Red Bull because of their history of antagonism with engine partners.
However, it is understood there is some support for the idea of supplying Red Bull within the company on the grounds that it could be advantageous to be associated with a brand which has a youthful image.
But Mercedes F1 boss Toto Wolff has made it clear he would not consider entering any talks with Red Bull while they still have a contract with Renault.
Mercedes and Renault are partners - each owns 5% of the other and they are collaborating on 10 projects in the road-car arena.
Red Bull's only other option if they split with Renault is to sign a deal for Ferrari to supply engines.