Renault Sport Racing managing director Cyril Abiteboul has warned Red Bull and Renault could be "out of sync" with power unit specifications.
Red Bull attempted to end its partnership with Renault last season but was unable to secure a power unit supply from another manufacturer, so instead will carry Renault engines branded as Tag Heuer in 2016.
Helmut Marko recently told Renault it should prioritise Red Bull over its own works team, and Abiteboul says the regulations prevent it from denying a customer from having the works specification.
"Yes it will be the same," Abiteboul said if Renault and Red Bull would have the same engine. "We have a mandatory obligation to do that from a regulation perspective it has to be the same."
However, when asked if there would be any difference in developments, Abiteboul highlighted there is a chance the works team could be running a newer specification of power unit than Red Bull.
"We are doing one development and as soon as they are ready they will be introduced into either car. We still have the engine pool to manage and the Renault and Red Bull team may be out of sync in that respect, but apart from that it is compulsory in the regulations to have the same equipment in the four cars."
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