Mr Waks alleges he was sexually assaulted by a former member of Melbourne's ultra-Orthodox community, Velvel Serebryanski, when he was a child in the 1980s.

The advocate, who has been a fixture in high-profile child sexual abuse cases, told police in 1996 that Serebryanski abused him when he was 11 or 12 years old.

Victoria Police informed Mr Waks on Thursday that Serebryanski had been arrested in New York and would face extradition to Melbourne.

Mr Waks alleges the former Melbourne community member was the first of multiple people to abuse him.

"I'm filled with so many feelings and emotions right now, especially relief and vindication," Mr Waks said.

"I'm not sure that I genuinely believed that this day would actually arrive - but I continued to hope and to fight for justice.

"Most victims/survivors of child sexual abuse never get any justice for the crimes that were perpetrated against them, in fact, most never even disclose the abuse they endured."

Victoria Police confirmed Bayside Sexual Offences and Child Abuse Investigation Team was investigating an alleged sexual assault that happened in the 1980s at a St Kilda East school.

"On 19 April 2023 a 59-year-old man was arrested and detained in New York in response to an extradition request from Victoria Police," a police spokeswoman said.

"The investigation remains ongoing."

Mr Waks said he would do everything he could to see through the justice process and also hold his alleged abuser's "facilitators" to account.

"Tzedek Tzedek Tirdof' - 'justice you shall pursue'," he said.

The advocate is chief executive of VoiCSA, an organisation aimed at combating child sexual abuse within Jewish communities.

Australian Associated Press