Update: All four have since been released without charge.
A file is to be sent to the director of public prosecutions and an investigation is ongoing.
Gardai had arrested four men in relation to an assault that happened in South Dublin. The incident occurred in Rathmines in the early hours of Sunday.
The four men were arrested in relation to an alleged sexual assault and were being detained at three garda stations in the DMR south region.
A garda spokesman said: “Gardai are investigating an assault that took place in Rathmines, Dublin 6, in the early hours of Sunday morning November 10.
“Four males have been arrested in relation to this and are being detained in three stations in the DMR South region.”