Police Commissioner Andy Tsang arrives for Legco meeting. Photo: RTHK.

Mr Tsang also rejected allegations that the police had detained three student protestors during the vice-premier's visit to the University of Hong Kong. Alumni and students of the university have condemned the police action, saying the detentions were illegal.

Mr Tsang said police officers were merely "assisting" university security guards to handle student protestors.

He also defended the use of "core security zones" in several locations, saying the term was not slang or jargon. He said it was understood by police.

However, a pan-democrat legislator, Lee Cheuk-yan, accused Mr Tsang of defending the indefensible.