Newport Gwent Dragons have claimed Ulster fans racially abused the Welsh side during Friday night's Magners League game in Belfast.
Dragons wing Aled Brew made a complaint during the game
The Dragons said a minority of the crowd was involved in the abuse and they will express their "concerns and disappointment" to Ulster.
Ulster chief executive Michael Reid acknowledged that Dragons wing Aled Brew made a complaint to a touch judge.
But he claimed that this was an isolated incident in Ulster's 14-7 win.
In a statement the Dragons make clear their desire for racial abuse to be eradicated from the sport.
"Following a strong performance against Ulster the game was somewhat soured when the Newport Gwent Dragons team were singled out for racial abuse by a minority of the Ravenhill crowd," they said.
"The issue having been raised by the players at half-time was then taken up by the Dragons management and brought to the attention of the Ulster officials.
"The Dragons will confirm in writing to Ulster their concerns and disappointment over the incident.
"The Dragons realise that it was a small minority but feel the issue needs to be raised as is not acceptable in society and the game of rugby football."
Ulster official Reid told the Sunday Times that action will be taken if there is "provable" evidence of racial abuse.
But he has hit out at the Dragons for releasing a statement on the claims.
"I'm amazed that the Dragons would have done it in this manner, rather than writing to me, or emailing me," he said.
It was an isolated incident, one person shouted something at one player.
"Normally any complaint of this nature would go through the Magners League association.
"The touch judge hadn't heard anything and that was it as far as I was concerned - I'm totally bamboozled.
"Gethin Jenkins (the Dragons commercial manager) said he would take stock and talk to me on Monday.
"It was an isolated incident, one person shouted something at one player.
"Suddenly, it's chanting at two players, one of whom wasn't even on the pitch in the first half (when the abuse is alleged to have taken place)."
The allegations come just a month after an Ulster fan was allegedly assaulted by Toulouse lock Trevor Brennan during a Heineken Cup game in France.
Brennan had been warming up with the Toulouse substitutes when he claims he was verbally assaulted by a group of Ulster fans.
Brennan faces an ERC disciplinary hearing on 26 February over the incident.
Toulouse back and former Wales captain Gareth Thomas was suspended for four weeks after "aggressively attempting to enter one of the seating areas" and "making offensive hand gestures" in the same incident.