Formula 1's governing body is keeping an eye on the emergence of alliances between the teams.
"This is something we need to worry about and we will discuss it," FIA race director Charlie Whiting is quoted as saying by France's Auto Hebdo.
"The relationship between Haas and Ferrari started the movement and we knew this was possible. This grey area has since been cleared up for new entrants and won't happen again.
"But we hear that there are alliances between the teams and I think we need to look into it closely."
The 2018 calendar continues this weekend with the Singapore Grand Prix.