The Hong Kong police arrested 23 people over charges of assaulting police officers and possession of offensive weapons in an operation Monday, a police spokesman said on Tuesday.

Kong Wing-cheung, senior superintendent of the Hong Kong police's public relations branch, told a media briefing at the police headquarters that the arrests occurred at Lei Yue Mun Plaza, and the Mass Transit Railway (MTR) stations at Lok Fu and Lai King, as well as the Mong Kok areas.

Kong stressed the MTR has obtained an injunction order issued by court and those suspects were in blatant violations of the order and challenged the rule of the law.

Dozens of radical protesters besieged the Mong Kok police station, hurled hard objects and aimed laser beams at the police station Monday night. After it was apparent that the police's warnings were futile, officers fired a shot of tear gas in the dispersal operation and made the arrests, he said.

To date, a total of 1,140 suspects have been arrested since June 9 when widespread unrest began to ripple through Hong Kong and caused mayhem, according to police.

Two police officers were injured during the operation on Monday, Kong said.

A total of 31 people were arrested in relation to the violence at MTR's Yuen Long station on July 21 and four suspects were charged with rioting, he said.