Bath say they will "ensure appropriate action is taken" after a supporter allegedly gained access to the officials' dressing room and confronted referee Greg Garner following Friday night's Aviva Premiership clash against Saracens.
Bath's stance follows confirmation from the Rugby Football Union to Press Association Sport that they have launched an investigation.
In a statement, Bath said: "Bath Rugby are aware of an incident involving the match officials which took place after the game against Saracens last night.
"In conjunction with the RFU and Premiership Rugby, the club is currently investigating the incident and will ensure appropriate action is taken."
Garner had earlier sent off Bath's England back Anthony Watson for a dangerous tackle on Saracens' Alex Goode as the west country club crashed to a 30-10 home defeat.
It is understood that a male fan made his way into Garner's room, which is situated close to the players' changing rooms at the Recreation Ground.
"I can confirm that we are investigating," an RFU spokesperson told Press Association Sport.
Garner consulted television replays before brandishing a red card, but Watson was furious as he left the pitch, reacting in disbelief at the official's decision and appearing to have words with Saracens wing Chris Ashton, who had pushed him following his challenge on Goode and seemingly impeded him beforehand.
Speaking after the game, Bath head coach Mike Ford said: "By the letter of the law, it is a sending off, isn't it? He (Watson) got underneath Alex, and Alex landed awkwardly.
"You get underneath the guy jumping, take his legs away and he lands awkwardly like he did, it's a red.
"Anthony is gutted. He was going for the ball, Ashton checked his run, and then all of a sudden he is underneath the player. It was an accident.
"We will have a look at it. We will fight his corner."
And Watson also found an ally in Saracens rugby director Mark McCall, who added: "The letter of the law says it is possibly a red card, but I feel sorry for Anthony because it was not intentional.
"His route to Alex was slightly disrupted by one of our players. He had to change course, he doesn't time it well, but it was what it was. It didn't change the course of the game."
Ford and McCall, meanwhile, played straight bats to suggestions of two unconfirmed alleged gouging incidents during a second-half maul.
Ford said: "The mauls, if you have ever been in one, there are arms and fingers flying all over the place. I doubt very much there is anything untoward there."
And McCall added: "I have come straight here (to the post-match press conference). I shouldn't comment on something I haven't seen."