Fianna Fáil leader Micheál Martin joined a victim of sexual abuse today in accusing Sinn Féin leader Gerry Adams of "despicable behaviour" in denying her account of how she was treated by the republican movement.

Belfast woman Maíria Cahill met Mr Martin at Leinster House today in the wake of the BBC Spotlight programme which detailed how she said she was raped in 1997 while a teenager and later and later interrogated by the IRA about her case.

Both later spoke to the media after Mr Adams had gone on RTE's "News at One" to deny Ms Cahill's claim that he forced her to confront her alleged rapist, a senior republican.

In response Ms Cahill said: "I am appalled. Gerry knows the truth. He knows I know the truth. I have been forced into the position where I have had to waive my anonymity because of his previous denials on that issue and I think that is reprehensible."

She commended the Spotlight programme for making the documentary about her case.

“I also think that Gerry not only owes the victims across the board an apology for how the IRA and Sinn Féin handled this issue. He also owes Micheál Martin a public apology because he called it a ‘new low’ after he raised this issue in 2012.

"And his party colleague Pearse Doherty came out and said those claims were unfounded and untrue. And I think at this point Sinn Féin needs to come out and say that the IRA internally investigated sex abuse cases that Sinn Féin members were involved in some cases in that."

Ms Cahill said that very prominent senior figures in Sinn Féin including Gerry Adams who was an MP at the time learned of her allegations. “Gerry had a duty to report that to the police and he did not do so.”

She said there were other women and men who had been treated in the same way. “I have met with victims in similar situations and I also have met with former senior Provisional members of the IRA who confirmed that they internally investigated cases of abuse. I think at this point it is completely ludicrous of Sinn Féin to keep denying the issue.”

She also pointed to the fact that Mary Lou McDonald had previously called on anybody within the Catholic Church who had been found to have covered up abuse to be arrested and prosecuted and face the full rigours of the law.

“I am challenging Mary Lou McDonald to come out again and call on those members within Sinn Féin currently, and I don’t think there is any doubt about this, who have been found to have covered up cases of child sexual abuse to be arrested, prosecuted and face the full rigours of the law. Nobody should be above the law on this issue.”

Ms Cahill said it was important that she had live witnesses who can corroborate it. “Gerry has chosen two dead people and I think that is absolutely reprehensible given his close relationship with those two people. That he has told lies about them and he has lied about me and he clearly has trouble with some aspects of his memory and it is not just on this issue but on other issues in the past just like he denies his membership of the IRA which I also know not to be true.

“The time has come where he needs to come out and say yes this was an issue; yes it was wrong; no Maíria Cahill is not a liar and that is the starting point for them.”

Mr Martin said that he had met Ms Cahill in 2012 and she had given him a very comprehensive account of her case.

“Her fear was that it would never see the light of day or get through. Unfortunately it has come to pass in that way and what is very clear from my perspective, I did make a public statement, some time back in relation to how Sinn Féin/IRA dealt generally with victims of sexual abuse very similar to the Catholic Church. The institution came first.

“I think Sinn Féin and Gerry Adams have very serious questions to answer. What role did the IRA play? There clearly was an internal kangaroo court operated by the IRA to keep Maíria quiet and silent on this.

“Today both Maíria and I listened to Gerry Adams on RTE1 and I just watched the reaction of Maíria to it. Disbelief in terms of his comment that he didn’t know her very well.

“He did a despicable thing in my view in that he attempted to undermine her when he referred to self-harm in 2002.”

Mr Martin said that the one thing people should never do in a situation like this was to try and undermine the person involved.

“You don’t in a very underhand way try to undermine the credibility or the character of the person involved and I think that was absolutely despicable that that happened today on the News at One.

“There are a number of key factors here. The first is that a decision was taken here that this case would not be reported to the police by Sinn Féin and the IRA. They attempted to deal with it internally and in an appalling manner.

“There was not full cooperation with the police from a lot of parties and then the police investigation itself left a lot to be desired. I know that will be the subject of an investigation by the Ombudsman.

“Sinn Féin needs to deal with tis past in this regard because we all remember the clarion calls from Sinn Féin spokespeople for Church people to resign their positions in relation to similar situations.

“There is no doubt in my mind and we have had other people coming forward in a similar context and the bottom line is this: that they dealt with these issues internally to try and suppress any emergence of the truth in relation to these issues for the purposes of preserving intact the reputation of Sinn Féin/IRA.

Mr Martin said that Ms Cahill had made a comprehensive and compelling case and Sinn Féin needed to face up to it.

“Stop denying and tell us the truth. I don’t know how many more times Gerry is going to prevaricate, obfuscate and simply not tell the truth about things.”