A self-confessed paedophile who sexually abused several boys in Sydney is being harboured by a leading Los Angeles Jewish welfare group.

The man, who is being investigated by NSW detectives over several sexual assaults at Bondi's Yeshiva school in the 1980s, has been shielded from exposure and scrutiny by Jewish Family Service of Los Angeles.

The service, more than 150 years old, provides medical, housing, food, counselling, educational and family support services.

Emails obtained from US sources show that since mid-2011 its board members have been aware of the man's sexual abuse history in Australia but have not reported him to authorities in Sydney or the US.

In an email to the man in November 2011, Debbie Fox, executive director of the Los Angeles organisation, refers to phone calls to board members about his activities in Sydney.