Chinese state media praises Hong Kong police 'restraint'

State media in China on Tuesday said the People's Liberation Army was on hand if necessary to support police in Hong Kong as it praised the force for its "restraint", the day after an unarmed pro-democracy protester was shot.

The city witnessed one of the most violent days yet in five months of pro-democracy unrest on Monday, with a police officer shooting a masked student protester and a pro-Beijing man set on fire.

The nationalistic Global Times newspaper told the police to "be tough" and said it "firmly supports" their actions.

"When necessary, the People's Armed Police Force and the People's Liberation Army Hong Kong Garrison will back you up in accordance with the Basic Law," the commentary read, referring to Hong Kong's mini-constitution.

China has stationed thousands of troops over the border from Hong Kong in the mainland city of Shenzhen, prompting concerns Beijing may intervene to end the unrest.

The state-run China Daily said Hong Kong police had shown "forbearance and restraint" over the last five months -- which it said seemed to have encouraged the protesters to more violence.

"The leniency Hong Kong judges have so far demonstrated toward the offenders... has also served to encourage terrorist acts," the newspaper said in an editorial Tuesday.

Footage of Monday's shooting -- broadcast live on Facebook by a bystander -- showed a police officer shooting an unarmed masked protester who approaches him.

The Global Times said the officer "had to open fire under the circumstances", calling the protester a "thug".

In a separate horrifying scene, a masked assailant doused a man with a flammable liquid and set him ablaze during an argument, with the video quickly spreading across social media.

"Claiming democracy and freedom, the rioters cannot tolerate people who express different perspectives," said the tabloid.

The newspaper warned protesters: "You are on the edge of doom.... walk away as soon as possible while you can still make the call."