St George Illawarra Dragons coach Paul McGregor is facing a $10,000 fine for calling match officials "embarrassing" and "incompetent" after an NRL loss to Newcastle Knights last weekend.
McGregor let his feelings be known after Tim Lafai and Nene Macdonald had tries ruled out by the bunker in a 21-14 defeat against the bottom side at McDonald Jones Stadium on Saturday.
The NRL on Tuesday issued McGregor with a breach of notice and proposed he should pay a hefty fine for his outburst.
"In simple terms, the rule is that coaches, players and officials should not discuss referees and their performances in the public domain," NRL head of football Brian Canavan said.
"We have been pragmatic in dealing with instances where comments have been made but the competence and integrity of referees has not been questioned.
"But it is our view that these particular comments crossed the line.
"All coaches should be aware that they risk sanctions if they discuss the performance of referees."
The Dragons have five working days to respond to the charge.