Australia's most senior-ranked Catholic clergyman has apologised for after a debate in which he appeared to suggest that Jews were intellectually and morally inferior.

Cardinal George Pell of Sydney debated with popular atheist Richard Dawkins on religion and science. The cardinal, who says his points during the debate were poorly made, also drew attention for suggesting Germans suffered more greatly than the Jews due to the Holocaust.

He issued a statement following the ABC television debate, in which he called the Holocaust "a crime unique in history for the death and suffering it caused and its diabolical attempt to wipe out an entire people".

He also said, "My reference to 'morally' was interrupted, but as I would never describe the Jewish people at any stage as morally inferior to their pagan neighbours, I was attempting to establish a counter poise to my earlier comment when interrupted."

Pell, commenting on the emergence of the Jewish people as related in the Bible, suggested during the April 9 debate that God, "for some extraordinary reason," chose the Jews rather than their slave masters the Egyptians who were much more advanced.

"Normally you go to a busy person because you know they'll do it and so for some extraordinary reason God chose the Jews. They weren't intellectually the equal of either the Egyptians or the [Persians]...," he said.

Cardinal Pell, who also serves as Sydney's archbishop, went on to address how one was able to judge whether the ancient Jews were intellectually and morally comparable to the ancient Egyptians.

"[...] you see the fruits of their civilisation. Egypt was the great power for thousands of years before Christianity. Persia was a great power, Chaldea. The poor - the little Jewish people, they were originally shepherds. They were stuck. They are still stuck between these great powers," Pell said, before moderator Tony Jones interrupted.

"But that's not a reflection of your intellectual capacity, is it, whether or not you're a shepherd?" Jones asked, which drew heavy applause from the audience.

Pell responded in the negative, but noted that "it is a reflection of your intellectual development, be it like many, many people are very, very clever and not highly intellectual but my point is..."

Asked if Jesus was among those whom Pell called "very, very clever and not highly intellectual," the cardinal said that Jesus did not come into the world as a "philosopher to the elite", but gave much of his attention to the poor.

"Jesus, I think, is the greatest, the son of God but, leaving that aside, the greatest man that ever live[d] so I've got a great admiration for the Jews but we don't need to exaggerate their contribution in their early days."

Jones then asked why God, said to be omnipotent and all powerful, does not intervene in modern times as He did in biblical times, as exemplified with cases of genocide, famine or the Holocaust.

"Well, that's - I think revelation is complete. That's a mighty question," Pell said. "He helped probably through secondary causes for the Jews to escape and continue. It is interesting through these secondary causes probably no people in history have been punished the way the Germans were. It is a terrible mystery."

"There would be a very strong argument saying that the Jews of Europe suffered worse than the Germans," Jones countered.

"Yes, that might be right," Pell admitted. "Certainly the suffering in both, I mean the Jews there was no reason why they should suffer."

In his follow-up statement on the debate, the cardinal further explained: "At the back of my mind I was thinking about an answer the Jewish writer David Berlinski gave to atheist Sam Harris on why God did not prevent the Holocaust.

"Referring to the incredible destruction and loss of life that the Allies inflicted on Germany in the course of the war which Germany started, Berlinski observed that 'if God did not protect His chosen people precisely as Harris might have wished, He did, in an access of his old accustomed vigor, smite their enemies, with generations to come in mourning or obsessed by shame'.

"This is not to deny the enormous sufferings that the Germans caused to the other peoples of Europe. But Berlinski's thoughts point us to the mysterious ways in which great crimes are sometimes brought home to those who have committed them."

Despite public perception of his remarks from the debate, Cardinal Pell emphasised in his statement that it was no secret that he holds the Jewish faith in high regard.

"My commitment to friendship with the Jewish community, and my esteem for the Jewish faith is a matter of public record, and the last thing I would want to do is give offense to either. This was certainly not my intention, and I am sorry that these points which I tried to make on 'Q&A' on Monday did not come out as I would have preferred in the course of the discussion," he wrote.