Hong Kong police have denied a social media post which claimed a police officer was injured by another officer and not protesters during clashes at the Legislative Council building in the early hours of Monday.

A video on social media which went viral captured the live TV broadcast of violent clashes when a group of protesters tried to storm the building while police with batons attempted to disperse the crowd, Sky Post reported.

A male voice recorded in Cantonese asked “why did he hit his own people?”

The video then showed a man suspected of being an undercover policeman stopping and separating other police officers. An officer with blood on his face, who was assisted by several other police, retreated from the frontline scuffle.

The report did not say who the voice belonged to. People shared the video on social media and asked if the police had played a trick to make the protesters look bad.

However, police refuted the claims at a press conference on Monday, emphasizing that eight officers were injured by objects thrown or from being kicked by protesters during the clashes.

Kong Wing-cheung, a senior superintendent of the Police Public Relations Branch, said eight police officers aged between 22 and 44 were injured. One of the policemen suffered injuries to his right eye and required 15 stitches.

Police arrested 19 people – mostly in their 20s – after Sunday’s massive rally against the controversial law amendment.

A total of 265 men and 93 women who were cornered by riot police after they allegedly occupied Gloucester Road in Wan Chai were released after giving all their personal information. Of the group, 80% were aged between 16 and 25 and 24 were below 18.