A woman who claims she was sexually abused by a school chaplain when she was a secondary school student has claimed before the High Court he performed oral sex on her in the school oratory.

The woman said she was a fifth-year student at the time and was wearing her school uniform and, after the sexual activity, both of them got ready for a sixth-year graduation Mass. The chaplain was 20 years older than her, she said.

The woman, under continued cross-examination on the sixth day of her case by Miriam Reilly SC, for the then chaplain who has since left the priesthood, said this was the first time they had oral sex on the school premises.

She said she was helping out at the sixth-year graduation Mass. When the chaplain was writing his speech in the oratory, there was “touching” and he then performed oral sex on her, she said.

When Ms Reilly put to her this did not happen, the woman said she knew it happened and said the priest had performed oral sex on her.

When counsel asked was this not “very risky”, the woman replied: “Everything about this relationship was risky.”

In her civil action, the now 28-year-old woman alleges that, between 2004 and 2007, she was repeatedly and wrongfully physically and sexually assaulted, falsely imprisoned and sexually abused and subjected to sexualised behaviour by the Catholic chaplain, who was also a teacher in her secondary school.

In civil proceedings, she has sued the man, who left the priesthood some years ago, for damages, including aggravated damages. He denies the claims.

She also sued the school and the local bishop who both deny any liability.

Mr Justice Robert Eagar has been told the school pleads it is not vicariously liable for any alleged actions of the priest and contends the diocesan bishop is liable.

The case continues next week.