Cybercrime detectives are investigating a “major data breach” at the NSW Department of Communities and Justice.

Police were alerted on Tuesday after about 9000 sensitive court files, including apprehended violence orders and affidavits, were downloaded.

The breach stemmed from the NSW Online Registry website, a secure platform that provides access to information about civil and criminal court cases.

“Cybercrime detectives commenced an investigation under Strike Force Pardey and are working closely with DCJ in order to contain the breach,” NSW Police said.

“Investigations remain ongoing to establish the full extent of the breach.”

The Department of Communities and Justice says it takes data security “extremely seriously”.

“DCJ acted with urgency to identify the breach and implement mitigation strategies to contain it,” a statement said.

It adds none of the data has yet been made public. “DCJ is now assessing the documents involved and will contact affected individuals as quickly as possible.”