The state government will launch an immediate investigation into an "appalling" data breach that saw personal details of emergency services staff posted to the web.

The breach reportedly occurred in October and saw private details – including addresses and medical information – of staff from a number of departments shared online.

“This kind of cybercrime is nothing short of appalling,” said Victorian Minister for Emergency Services James Merlino.

“There will be a thorough, independent investigation to determine exactly how this happened and it will be dealt with accordingly.”