The FIA has agreed to allow a re-equalisation of engines in Formula 1 next year if teams believe it is necessary, but has said moves will only be done so by pegging back the best power units.
Last year, Renault was allowed to re-tune its engine to help bring its performance up to the level of its rivals - with some manufacturers having benefited from minor tweaking during the engine freeze.
Calls for a further parity re-emerged after the Italian Grand Prix, when many teams believed that Mercedes-Benz had opened up a clear advantage at the front of the field.
Red Bull Racing team principal Christian Horner told AUTOSPORT at Monza: "I think it is something that perhaps needs to be carefully looked at.
"The FIA has all the information they can see where the differences are on, I don't think it is a coincidence that you have three Mercedes-powered teams that dominated six out of the top seven places in qualifying and looked dominant again here in the race today.
"So, the FIA I am sure, they have all that information to hand, but it is always the danger of a freeze that you can freeze in a competitive advantage."
Teams are set to discuss the matter soon and the FIA has made it clear that it will allow changes to be made if there is agreement from the outfits. But parity will not be brought about by bringing the worst power units up to the level of the best.
In a statement issued after the FIA World Motor Sport Council hearing on Monday, the governing body said: "Following suggestions that there is a differential between the performance of engines used in Formula 1, the World Motor Sport Council has decided that should this be the case, and should the teams wish to eliminate this performance differential, they may be allowed to do so by reducing the performance of the more powerful engines. However, no engine upgrades will be allowed."
Should this scenario happen, it could result in Mercedes-Benz being forced to make changes to its engine to bring its performance back down to the level of its rivals - although achieving this will be far from straightforward.