The Football Association is looking into the comments made by Liverpool boss Brendan Rodgers following his side's 2-1 Boxing Day defeat at Man City, Press Association Sport understands.
Rodgers, furious with a number of decisions made by the officials during the Barclays Premier League contest, appeared afterwards to question the integrity of its referee Lee Mason.
The manager said the officials' performance was ''horrendous'' and expressed his surprise that, in Mason, a referee from Bolton - barely 14 miles from Manchester - should have been in charge of the game.
''I was surprised we are playing in Manchester and have a referee from Greater Manchester,'' Rodgers said.
''I am sure we won't get (for) Liverpool-Man City someone from the Wirral.
''I thought they were horrendous in terms of performance.
''Hopefully we don't have another Greater Manchester referee again on a Liverpool-Manchester game.''
Of the many incidents which left Rodgers unhappy, the most notable was the one which saw Raheem Sterling flagged offside when he was at least two yards behind last defender Aleksandar Kolarov before racing through to face Joe Hart.
''The officials make mistakes, I just felt the mistakes made shouldn't have happened at this level. This is a big game,'' he added.
''It was a poor decision and of course Raheem goes through and scores.
''I thought we never got any decision. The linesman on the offside one - he wasn't even on the same cut of grass.
''If you're working at this level you have to get it right. It's not even a difficult one.
''It is a perfectly-timed run and he is given offside when he is through one-on-one on goal. These are big moments in big games.
''There is another incident when Luis (Suarez) doesn't get a free-kick when Joleon Lescott went right through him.
''It is arguable it is a penalty at the end. Luis Suarez can't jump because he (Lescott) is tugging at his shirt.''