Malone Rugby Football club has said an investigation is under way after an "inappropriate" photograph emerged of two of its players.
The picture shows two men, one in his underwear, holding a trophy between their crotches.
They have the name badges Paddy Jackson and Stuart Olding stuck on their chest. The Ulster and Ireland internationals were both acquitted of rape last month.
The club apologised for any offence caused.
It is understood the players were celebrating their Easter Monday McCrea Cup win against Cooke rugby club.
The match took place at Kingspan stadium but there is no suggestion that Ulster Rugby has any connection to the incident.
Ulster Rugby told the BBC that they 'have been in contact with representatives from Malone RFC, who have advised that they are carrying out a full investigation.'
Malone RFC's full statement said: "It has been brought to our attention that an inappropriate photograph involving Malone players has been posted on a private social media site.
"Malone was unaware of the photograph and will investigate how it occurred.
"The Club apologises for any offence caused by the contents of the photograph.
"A full investigation will now take place by Malone RFC."