Australia's most senior Orthodox rabbi resigned this morning from two top posts in the community after a royal commission into child sex abuse heard that he called the father of three abused boys a "lunatic".

Rabbi Meir Shlomo Kluwgant resigned as president of the Organisation of Rabbis of Australasia, which is resolutely conservative on issues such as gay marriage. He also resigned as a general manager at the leading charity Jewish Care Victoria and lost his place on the Victoria Police multi-faith advisory committee

In a text to Australian Jewish News, he had said that Zepheniah Waks, the father of 17 sons including whistleblower Manny Waks and two others who were abused, was "killing" the Chabad community.

He sent the text as Zephaniah Waks was telling the commission how his family was ostracised and bullied after detailing the abuse that was endured at Chabad's yeshivah centre in Melbourne.

In the text, Klugant continued: "Zephania is attacking Chabad, he is a lunatic on the fringe, guilty of neglect of his own children. Where was he when all this was happening?"

Manny Waks, who has felt able to speak out because he has left the community, welcomed the resignation.

He told The Guardian: "I hope this is his first step towards educating himself about child sexual abuse and that he can contribute towards being a part of the solution to it from now on.

"But he is unfit to hold any leadership position. As he holds several high-profile positions within the Yeshivah community, I feel he should resign from them all."

The director of the Sydney Yeshivah centre, Rabbi Yosef Feldman, also resigned last week after his evidence caused offence to child sex abuse victims and members of the Jewish community.

The commission has been investigating how schools, churches, sports clubs and government organisations responded to allegations and instances of child sexual abuse since 2013.

Eighteen months ago the Organisation of Rabbis of Australasia issued a statement on child sexual abuse timed for Yom Kippur, begging forgiveness from victims and condemning cover-ups.