The 34-year-old was led away from the Kingsholm Stadium following Connacht's meeting with Gloucester Rugby on Friday night, before later spending 20 hours at Cardiff Bay Police Station.
It is alleged that the incident in question took place in the Welsh capital last month.
Simon Porter, the agent of Muliaina, claimed that the arrest came as a "complete shock" to the player, adding that the full-back thought that he was simply being taken away for a random drug test.
"He had a night in the police cells, he's pretty distressed, trying to deal with it, and it came as an absolute shock to him," Porter is quoted as saying by TVNZ.
Muliaina, who played 100 tests for the All Blacks, categorically denies the allegation and is expected to travel back to Ireland while police continue to conduct their investigation into the matter.