Secretary for Education Kevin Yeung says freedom of speech should be exercised legally and bounded by moral principles.
He made the comments to the media today after offensive posters were found on the Education University's campus following the death of Under Secretary for Education Choi Yuk-lin's son.
Mr Yeung said the incident has concerned him as the university is a teacher-training institution.
"I think one of the principles is what they post on the board should be something that is morally sound and also legal, so I will leave the details to the university and the student union to work out.
"I think one very basic principle is, when we talk about freedom of speech, we are talking about the freedom but not without restriction. There are also moral and legal considerations."
On posters advocating independence for Hong Kong on various university campuses, Mr Yeung said separatist calls violate the Basic Law.
