A West Coast man was abused at the hands of the Catholic Church during the 1950s.

In a "very rare" ruling, the Catholic Church has found a nun guilty of sexually abusing a child in her care, it has emerged.

Following an inquiry, the Catholic Church has ruled Mother Lucia guilty of historic sexual and physical abuse against a Christchurch schoolboy "on the balance of probabilities". The prioress died in 1997, aged 90.

In November 2015, a West Coast man, who did not want to be named, brought complaints against the Sisters of Our Lady of the Missions under the church's Path to Healing protocol.

MARION VAN DIJK/FAIRFAX NZ Nuns from the Sisters of Our Lady of the Missions were involved in primary schools throughout New Zealand.

He attended the Addington Convent School, now called Sacred Heart School, from 1956 to 1963.

READ MORE:

* Nuns 'stole child's innocence'

* Spotlight film encourages victims to disclose sexual abuse

* Predator priests and pay outs - why the church investigates its own

* Catholic rape survivor: I want a Royal Commission into clergy sexual abuse

"They stole my innocence as a child. They robbed me as a child. They robbed me of an education and they f..... up my life completely," he said.

CHRIS SKELTON/FAIRFAX NZ Bill Kilgallon is tasked with leading the effort to investigate and resolve allegations of abuse for the Catholic Church.

The church's National Professional Standards Response Committee (NPSRC) found that "on the basis of the evidence before it that on the balance of probabilities you were abused both physically and sexually by Mother Lucia", whose given name was Eileen Reilly.

The man's second complaint relating to physical abuse by the late Sister Hilary, whose given name was Catherine Moriarty, was not upheld.

"The committee did not find on the balance of probabilities that you were physically abused by Sister Hilary."

MARK TAYLOR/FAIRFAX NZ The Sisters of Our Lady of the Missions have accepted that a nun sexually abused a Christchurch school boy in the late 50s.

Three weeks ago, the man received an apology letter "out of the blue" from the Sisters of Our Lady of the Missions, alongside the ruling.

Sisters of Our Lady of the Missions province leader Carmel Cole offered to pay for counselling and meet with him, but the man said the "damage is done".

"I don't want to meet with them. It's a bloody insult and I just don't wish to see them ever again."

Cole refused to comment, and would not release records for Mother Lucia and Sister Hilary.

The man recalled the sexual abuse he was subjected to by Mother Lucia through tears, saying it started when he was 8 years old when she ordered him to remove his clothes so she could check for polio.

In a separate incident, she asked him if he had been circumcised, then ordered him to remove his shorts. He had an erection, after which she told him he was a "dirty little boy" and hit him.

Over a nine-month period, she fondled, hit and cuddled him.

The abuse continued until he refused to enter the classroom. He left the school soon after.

NPSRC New Zealand director Bill Kilgallon​ said he was not aware of any other complaints relating to the two nuns.

Kilgallon said they would investigate "if anybody else comes forward".

Cases where nuns were the perpetrators of sexual abuse "were very rare".

"If you look at most of the research, sexual abuse in institutional settings is generally 90 per cent male."

Kilgallon said the department, established to oversee the response to complaints of abuse, averaged 22 complaints a year.

"Organisations dealing with that, whether it's the state or the church, have to really look very carefully at the way we look after children . . . and learn the lessons of the past."

Retired Christchurch-based policeman Paul Fitzharris had been contracted by the Catholic Church to investigate several separate complaints over the last five years, including the West Coast man's.

He said it was not the first case alleging abuse by a nun that he had been asked to look into, but more often than not they involved allegations of physical abuse.

Male Survivors of Sexual Abuse Trust manager Ken Clearwater said the church's acceptance of the sexual abuse allegation came as a surprise.

"The fact it came out like it did – even though it took a long time – it was a good decision."

He said the church needed to continue to accept and acknowledge abuse committed by its members.

"Religion is built on compassion . . . these people have harmed these children when they were supposed to be looking after them."