Brendan Smyth (centre) admitted to sexually abusing children

One of the highest ranking members of the Catholic Church in Ireland has called for an independent investigation into past allegations of clerical sex abuse.

As Archbishop of Dublin Diarmuid Martin spoke out against the past failings of the Church, another bishop defended Cardinal Sean Brady, whose involvement in a secret 1975 probe into allegations of abuse has come under fire.

Archbishop Martin said a commission should be set up to examine all accusations against paedophile priest Brendan Smyth.

"I know it's not fashionable to talk about commissions, but I believe an independent commission to investigate the activities of Brendan Smyth, as to how he was allowed to abuse for so many years - north and south, church and state," Archbishop Martin told RTE, Ireland's national broadcaster.

"I believe that would be in the public interest."

He said it was the least Fr Smyth's victims deserve.

But Bishop of Ardagh and Clonmacnoise Colm O'Reilly said while the abuse carried out by Fr Smyth was appalling, Cardinal Brady acted accordingly and should not be forced to resign.

A documentary last week revealed that Cardinal Brady, who acted as a note-taker during the probe into allegations against Fr Smyth in the 1970s, had a list of children's names who were being abused but failed to inform Gardai and their parents.

He has refused to step down from his position as Primate, despite increasing pressure from politicians north and south of the border.

The cardinal gave the information to his superior bishop, but no action was taken against Fr Smyth and he was able to continue abusing children for a further 20 years.

"I feel he should not stand aside," said Bishop O'Reilly.

"I think what he did, he did conscientiously. I have no reason to doubt that. I have great respect for Cardinal Sean Brady."

The bishop added that had Cardinal Brady, then a teacher in Armagh, given the evidence he had obtained to Gardai, they would have referred him back to the Church.

"I'm not sure the authorities would have been able to take it on themselves," he said.

The 1975 private probe involved interviews with then 14-year-old Brendan Boland.

He told investigators at least five children had been attacked by Smyth.

Archbishop Diarmuid Martin (left) and Cardinal Sean Brady (right)

Fr Smyth continued abusing for a further two decades and it is feared at least another 30 children fell victim.

The paedophile was eventually convicted in 1994 in a Belfast court of 17 counts of sexual abuse.

He pleaded guilty to a further 74 counts of child sex abuse three years later in Dublin. He died in prison in 1997.