An investigation is to be carried out into a conversation between a number of gardai during which a number of them were allegedly recorded joking about raping a woman.
A complaint was made following the arrest of two women at a protest over the controversial Corrib gas project in north Mayo last Thursday.
Both were taken to Belmullet garda station but were released without charge. They sought and were given back a video camera they had with them at the time.
The women claim that when they replayed the recording some time later, they found it had apparently recorded the conversation between a number of gardai in that car.
Gardai confirmed last night that a superintendent had been appointed to examine the full facts of the matter.
The investigation will probe whether the recording, which lasts 37 minutes, is authentic and will examine its contents.
On the tape, a voice says that one of the women sounded like she was "a Yank or Canadian".
A second voice replies: "Well, whoever, we'll get Immigration f*****g on her."
Another person is allegedly heard saying: "She refused to give her name and address and was told she would be arrested."
"And deported," a voice replies, before another voice is alleged to say: "And raped."
A further voice allegedly says: "Give me your name and address or I'll rape you." Laughter is heard on the tape.
The women were arrested on a road in north Mayo after one of them had staged a protest at nearby Aughoose.
The woman had climbed on to the roof of a tractor which had been hired to facilitate preparatory work by Shell on the Corrib gas pipeline.
One of the women was carrying a video camera, but was forced to drop it by gardai.
The women have since complained that the gardai used unnecessary force in the arrest.
Both women were arrested for allegedly committing public order-related offences and a file is being prepared for the Director of Public Prosecutions.
A garda spokesman has confirmed that a senior garda from outside the Mayo Division has been appointed to establish the facts of the case.
The two women are to make a complaint to the Garda Ombudsman Commission about the incident.
Meanwhile, separate legal challenges aimed at quashing An Bord Pleanala permission for an onshore gas pipeline have been fast-tracked.
The challenges are being brought by An Taisce and two local residents in relation to the pipeline linked to the Corrib gas field.
An Taisce chairman Charles Stanley-Smith said the board's deliberations when granting the consent last January were not transparent. An Taisce had inspected the board's file and there were "glaring omissions", he said in an affidavit.