HONG KONG - The first suspect to plead guilty to rioting for participating in a violent protest last year was sentenced to four years in prison on Friday.

The sentence was handed down to 21-year-old lifeguard Sin Ka-ho by Judge Amanda Jane Woodcock at the District Court.

Sin took part in a protest outside the Legislative Council complex on June 12 last year, during which radicals blocked main roads, charged police cordon line, and attacked police officers.

Several officers were injured in the melee. A total of 11 people have been arrested.

In passing down the sentence, Woodcock said the "massive and serious" violence used in the riot cannot be tolerated in a civilized society.

Extreme and escalated violence has been used to attack police officers, who were heavily outnumbered by the protesters, she added.

Sin pleaded guilty to the offence on May 4. He denied two other charges of resisting a police officer.

In his plea, Sin said that he regretted what he had done and if he had a chance to talk to young people, he would urge them never to resort to violence.

A total of 8,337 people have been arrested since June 9 in connection to violent protests against the now-withdrawn extradition law amendment bill, police said Thursday.

Among these arrestees, more than 1,600 have been prosecuted — 595 with rioting, 252 with possession of offensive weapons, and 236 with unlawful assembly.

Police Commissioner Chris Tang Ping-keung said last week that 57 people of them had been convicted, including 15 who were sentenced to jail with terms of between two weeks and 14 months.