Waratahs coach Michael Cheika has been issued a warning by Super Rugby administrators after approaching a referee during his side's 23-11 win over the Blues in Sydney last month.

SANZAR has confirmed that it received a formal complaint with regards to a conversation that took place between Cheika and referee Jaco Peyper during the half-time break.

Last week Cheika was sent a letter from the competition's governing body, SANZAR, asking for an explanation for the move, which is a breach of World Rugby law 6.A.7 relating to who referees can speak to during a match.

The Waratahs coach asked the referee for clarification on a scrum ruling in front of other match officials, and although SANZAR has ruled that the conversation was polite and there was no breach of the code of conduct, both Cheika and Peyper have been issued with formal warnings.