Leaks of internal government data are unacceptable, the security chief has said after department personnel data was found in a common file-sharing programme.
The documents on Foxy - a free application popular in Hong Kong, Taiwan and on the mainland - included appraisals of workers in the fire services and food and environmental hygiene departments.
Speaking at the Standard Chartered Hong Kong Marathon, Secretary for Security Ambrose Lee Siu-kwong said: "[Leaking information] once is already too much."
He said the Fire Services Department had begun an inquiry into the leak. "We are very concerned about it," he said.
"It is not the first time that data has been leaked on Foxy. After previous incidents, the government issued detailed guidelines and raised the security level of our computers."
Web surfers can search for information on Foxy and download various types of shared files from other users.
Mr Lee said he was unsure why the incident had happened but would investigate it.
One of the files leaked is believed to be the appraisal report of fireman Siu Wing-fong, who died fighting a fire in a Mong Kok bar last year.