Anglicare Sydney is reportedly being held to ransom over potentially sensitive information that has been lifted from the Not For Profit’s computer system.

17 gigabytes of data were stolen and transmitted to a remote location on August 31.

Anglicare said in a statement it had immediately investigated and engaged cyber security experts, and had an incident response plan for such events.

An investigation is still trying to determine the data contained in the files.

Anglicare Sydney said in a statement: "The main system relating to Anglicare Sydney's Out of Home Care program, which includes the foster care program, was not impacted."

NSW Police and the Australian Signals Directorate were also notified.