People involved with the university would be well advised to change their passwords immediately, after the attack which was spotted on Thursday.

UOW has not yet given details of the nature of the attack, which it called a "cyber security incident".

The attack was identified and contained on Thursday, but UOW did not reveal it to the public until Friday evening.

The Mercury asked UOW why staff and students weren't notified earlier than 6pm on Friday, and what advice there was for dealing with the hack.

A UOW spokesman said there was no further comment.

As of Saturday morning it remained unclear how many students and staff were affected, what kind of data was accessed, how long the breach had been going on, or whether people needed to take action to make their accounts secure.

The university has brought in outside experts to work on assessing and responding to the hack and said normal operations were continuing.

"UOW has identified a cyber security incident within our systems," the university's statement said.

"The incident was detected and contained yesterday, and it is likely that data was accessed.

"We are working to investigate the cause and extent of the issue. Our normal operations are continuing as we assess any potential further impact.

"We are committed to keeping staff and students updated and informed as this situation develops."

The university said it was in contact with relevant authorities and government regulators and would provide updates "as the situation evolves".