The FA had written to Roberto Mancini and Harry Redknapp over their criticism of referees after Manchester City and QPR's Boxing Day defeats.
The FA sent letters to City boss Mancini and Rangers counterpart Redknapp requesting their observations on their post-match comments in the wake of their sides' respective matches against Sunderland and West Brom.
Mancini and Redknapp could both find themselves charged by the FA if their words are found to have amounted to improper conduct.
Mancini hit out at referee Kevin Friend following City's 1-0 defeat at the Stadium of Light, saying: "Maybe the referee ate too much for Christmas."
The Italian was particularly angry with what he felt was a foul on Pablo Zabaleta in the build-up to Adam Johnson's winner, saying it was "impossible two men couldn't see it" in reference to Friend and his assistant.
Redknapp, meanwhile, was furious with what he claimed were two "scandalous" decisions in QPR's 2-1 home defeat to West Brom.
The Rangers boss felt the Baggies' second goal should have been disallowed for a push on goalkeeper Robert Green and bemoaned the decision not to award his side a penalty when Liam Ridgewell appeared to handle the ball late on.
Redknapp said: "I asked the linesman how he didn't see that penalty - it was the most blatant handball you could wish to see but he said it was murky down there in that corner and he couldn't make it out.
"Maybe he should go to Specsavers. I thought they were both awful decisions. Scandalous decisions."
what do you think?
Hang on so fergie can say what he likes AGAIN bur these two can't hypocritical FA
Because he's with the most well known team in the world and the rest are minor teams - so he says
Quite clearly ferguson confronted an official, why is he allowed to get away with it ?