Lawyers acting for the victims say the national royal commission announced by the Prime Minister on Monday was the only acceptable response to the legacy of institutional sexual abuse.

Jason Parkinson, of Porters Lawyers, has taken legal action throughout Australia against the Catholic and Presbyterian churches as well as the Salvation Army and the Church of England on behalf of victims.

He says the inquiry had to be nationwide to cope with the ''Chinese walls'' erected by institutions to avoid legal responsibility. Mr Parkinson said the scale of abuse of his clients, former students at Catholic schools Marist College and Daramalan College between 1976 and 2000, had left many of the city's young people ''terribly scarred''.

Mr Parkinson, who believes there were up to five abusers at Marist in the late 1970s and early 1980s, said there was little understanding of the effect the offending had on the community.

''The youth of Canberra, unfortunately, were greatly scarred by those abusers when you consider the size of Canberra and the number of sexual abusers from just those two schools,'' he said.

''That should give people an idea of what a serious problem this is throughout Australia and why we need a national royal commission.''

He said the commission must be cross-border to cope with traditional responses by institutions to allegations of abuse.

''It has to be done on a national basis because the Catholic orders transferred their paedophiles all around Australia through jurisdictions so they could avoid or stymie police inquiries,'' he said.

One of the offenders at Marist was John Chute, aka Brother Kostka, who taught at the school between 1976 and 1993 when he was moved to Sydney after a complaint from the parents of a victim. Chute later served two years in jail for 19 attacks on six boys.

Another abuser, Paul Lyons, who committed suicide after one of his victims went to the police in 2000, spent 12 years teaching at Marist Brothers before joining Daramalan in 1989. In both cases claims of abuse were made by parents, students or other teachers, but it is alleged they were ignored by the school and church hierarchies.

Mr Parkinson, a former policeman, said references to offending as ''historical'' was cruel and demeaning to victims.

''What really annoys me is when I hear these cases referred to as 'historical' because the fact is that I'm dealing every day with people who are referred to as historical,'' Mr Parkinson said.

''They're now in their 40s, 50s and 60s, there's no one older because they don't live that long after they've been sexually abused.

''They self-medicate with alcohol, drugs and gambling and their life expectancy is greatly reduced, so I hate it when they try to dismiss this as a historical problem for the Catholic Church.''