Some of Australia's most prestigious private schools are being sued for millions of dollars by men who allege they were sexually abused by teachers and staff.

Key points: The Scots College, Knox Grammar, Waverley College and De La Salle, Revesby Heights are being sued

The Scots College, Knox Grammar, Waverley College and De La Salle, Revesby Heights are being sued 10 claims have been lodged and another two will be lodged in coming months

10 claims have been lodged and another two will be lodged in coming months In one case abuse victims claim Scots College failed to protect them from "sexual predation"

Sydney lawyer Ross Koffel is bringing multiple claims for damages in the NSW Supreme Court against schools including The Scots College, Knox Grammar, Waverley College and De La Salle, Revesby Heights.

Mr Koffel told the ABC he had been approached by a large number of men who allege they were abused at private schools around the country.

"It just seemed to me to be the same problem in school after school after school and it surprised us how many schools, how many students are affected," Mr Koffel said.

"It is a systemic problem in the institutions, in the schools. We're alleging sexual abuse of the students during school hours in most cases and on the school premises, and it just really couldn't be worse."

Ten separate claims against The Scots College, Knox Grammar, Waverley College and De La Salle College, Revesby Heights have been lodged and another two claims will be lodged in coming months.

Mr Koffel said he is investigating another eight claims against other schools.

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Three men who were sexually abused by former Scots College teacher, John Joseph Beckett in 1989 have filed claims against the school.

Last year, Beckett was convicted and sentenced for sexually abusing the men on a school trip to the outback.

In court documents, the men allege Beckett was a "notorious paedophile" and that the school failed to protect students from his "sexual predation".

Victim told not to report abuse claims

One of the men, Tom Jackson told the ABC he complained to the school about the abuse.

"The response at the end was: 'Don't talk to the police, we'll deal with it. He won't take the tour again'," Mr Jackson said.

But Mr Jackson said Beckett remained at the school for another two years.

It was only when two witnesses to the sexual assaults spoke to police that Beckett was charged.

In a statement the Presbyterian Church of Australia on behalf of Scots College said: "These matters are now before the courts and the Presbyterian Church does not wish to make any statement that may impinge upon the independence of that process in the interests of those parties".

"We support those who have come forward to tell their story of what happened to them and we respect their courage in doing so."

Former De La Salle College, Revesby Heights student Adrian Coorie is also part of the multiple damages claims.

Mr Coorie alleges he was repeatedly sexually abused when he was in year five and six by the religion teacher, Errol Swayne.

Adrian Coorie when he was in year five. ( Supplied )

Swayne lived in a caravan on the school grounds and required Adrian Coorie to attend the school on weekends to perform chores.

During those visits, he showed the 10-year-old pornographic films and sexually assaulted him.

During school hours, he would frequently send Mr Coorie to his office for punishment, where he would indecently and sexually abuse him.

"He would explode in the classroom when sending me out," Mr Coorie said.

"I bet every student in that class felt that I'm a goner, I'm going to go up there and I'm going to be punished, so it was a role play on his behalf.

"So to get up there and then be relieved of any punishment and walk out, you feel protected and powerful and, like, wow.

"Nothing happened. So I think that was the way that he started the whole process."

A few years later, Swayne committed suicide.

Mr Coorie battled depression for many years and when he read about the royal commission, decided to give evidence in closed hearings. It was here he discovered that Swayne had abused other boys.

"After I had given my statement to (commissioner) McClellan he let me know that 'the teacher you're here about has been made known to us on a number of occasions before'."

"Even though it was quite naive sometimes you can think you're the only person something has happened to but that's not the case and that's where that was confirmed.

"That other people had already been there and spoken to the royal commission about the same person, so that was a bit of an eye-opener too."

Mr Coorie alleges the school failed to ensure his safety, failed to maintain procedures for the imposition of discipline and proper protocols for student-staff interactions.

In another claim filed against the prestigious Waverley Boys College, a man alleges he was sexually abused by a volunteer cadet officer.

He alleges he was assaulted by the officer when he was 16 years old, while on a camp in Yarramundi.

He said he reported the abuse to the school but his account was rejected as "false and dishonest". Soon afterwards, the officer was dismissed.

The plaintiff claims the school was negligent because it failed to conduct background checks and failed to adequately supervise cadet officers.

The man sought help from Ross Koffel after his wife came to him with enrolment papers for his son to attend the school.

"He broke down at that point, he was unable to sign them. He had gone to the school, his father had gone to the school, his ex wife's father had gone to the school, he couldn't bring himself to sign the papers and at that point, he rang me," he said.

Sydney lawyer horrified by royal commission evidence

Mr Koffel rose to prominence when he appeared at the royal commission for victims of child sexual abuse at Knox Grammar.

He was a Knox student himself and was shocked by what emerged at the hearings.

"It was horrendous," he said.

"I was deeply affected by what had happened because I had a recollection of the places, the rooms, the school, the playgrounds where it occurred. I knew a lot of the teachers by name. And I was just completely floored by what came out."

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The royal commission heard a group of paedophile teachers were abusing children at the school, many of whom have been charged and convicted of child sex offences.

Mr Koffel has filed three new civil claims against Knox Grammar, on behalf of men who allege they were abused by teachers in the 1970s and 1980s.

One of the plaintiff alleges he was sexually assaulted by the former principal of the Knox Preparatory School, Bruce Barret in 1980 - when he was just six years old.

He alleges he was caught walking on the grass and sent to Mr Barrett's office for punishment. A statement of claim filed to the NSW Supreme Court alleges Mr Barrett digitally penetrated the boy while another teacher, Barrie Stewart watched on.

The second plaintiff alleges he was sexually assaulted by teacher, Adrian Nisbett in 1976 and the third alleges he was assaulted by Barrie Stewart, on school grounds and at Camp Knox in 1985 and 1986.

Mr Koffel said he hoped to achieve proper compensation for his clients but also to bring about change in school procedures.

"I believe it will reinforce the schools' attitude to make change to have procedures to ensure that it never happens again, so that parents can with a degree of comfort send their children to school knowing that they will be safe," he said.

A Knox Grammar media spokesman said he was unable to comment while the claims were before the court.