A former New South Wales priest claims to have witnessed a "system of cover-ups" within the Catholic Church to hide child sexual abuse.

Kevin Lee was ordained as a priest 20 years ago and worked as a police chaplain for some of that time, but was relieved of his parish responsibilities in Western Sydney this year when he admitted to marrying a woman in secret.

His comments follow those of Detective Chief Inspector Peter Fox who told Lateline on Thursday night that the Catholic Church is involved in cover-ups and paedophile priests have destroyed evidence to avoid prosecution.

Mr Lee told Lateline on Friday that abuse is widely covered up in the church and that he first became aware of it as soon as he was in the seminary.

"People used to tell me and people in the first parish I was in started to confess their frustration with the authorities and the church for not dealing with the abuse that happened to their sons," he said.

"I became aware that some of the other priests were actually paedophiles and were not necessarily becoming priests because they wanted to help people, but because they were paedophiles who wanted the opportunity," he said.

Mr Lee says a church protocol was in place for dealing with cases of child sexual abuse, but it was not actually used.

"I saw a system of cover-ups, a system of blind-eye turning and just ignorance of the fact that it was happening," he said.

He says he took his concerns to superiors within the church but was knocked back.

"In my earlier years as a priest, I was having these people coming to me in confession or just sharing in counselling sessions their experience of frustration and anger with the church that had ignored their pleas of justice when their children had been abused and I started writing the notes down," he said.

"I was speaking to a barrister at one point and I thought he was going to help my case by putting it forward in some legal process.

"He said 'document everything you have', and everything I had I took to authorities within the church and I was told I needed more evidence."

Mr Lee says church authorities told him the allegation he brought them were hearsay.

"In the end I got frustrated with the fact that it was like the hierarchy in the Church was saying we don't believe you, you're a liar, you're making it up," he said.

Mr Lee says he has also taken his allegations to police and helped them with their investigations.

"I have given information to the police and I have also given information to the Catholic Church's independent inquiry," he said.

"One of the feelings I have about that information is that, again, I have been told it is hearsay. I didn't witness it.

"I have heard from people who have said to me that this happened and that is where the process gets bogged down."

Royal commission

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Mr Lee has echoed calls from Chief Inspector Fox for a royal commission into child abuse within the Catholic Church.

On Friday, NSW Premier Barry O'Farrell announced a special commission of inquiry into claims of police cover-up of church sexual abuse following Chief Inspector Fox's comments.

Chief Inspector Fox said he was not convinced a special commission would be as effective as a royal commission.

Mr Lee told Lateline he has spoken to victims who says they would speak at a royal commission if one was set up.

He says damage to the church's reputation will continue until a royal commission is held.

"If you try and encourage people to be involved in the church and yet there is an undercurrent of suspicion that all priests are paedophiles, then it's going to continue until there is a royal commission that says 'no, we're actually looking into the operation of the Catholic Church'," he said.