Chinese officials have urged protesters across Hong Kong not to mistake Beijing's "restraint" for weakness, as violent anti-government protests enter their third month and show no sign of abating.

Key points: Chinese officials said the protest "masterminds" would face punishment

Chinese officials said the protest "masterminds" would face punishment They called on Hong Kong residents to turn against the protesters

They called on Hong Kong residents to turn against the protesters Protesters held their own press conference and accused police of firing tear gas at residential buildings

On Tuesday, China's State Council Hong Kong and Macau Affairs Office held its second press conference on the protests in just over a week, with spokesman Yang Guang and spokeswoman Xu Luying saying it was "only a matter of time" before those who were behind the protest movement faced punishment.

"I would like to warn all of the criminals: don't ever misjudge the situation and mistake our restraint for weakness," their statement said.

A small group of violent radicals were at the forefront of the protests, with "some kind-hearted citizens who have been misguided and coerced to join" in the middle, they said, adding that anti-China forces were the "behind-the-scenes masterminds" who had "openly and brazenly emboldened" the protesters.

Mr Yang singled out "brazen, violent and criminal actors" and the "meddling hands behind the scenes" as the focus of law enforcement efforts, which indicates Beijing will take a hard line against the protests and has no plans to open a dialogue on activists' demands for political reforms.

Yang Guang said punishment for those behind Hong Kong's protests was "only a matter of time". ( AP: Mark Schiefelbein )

He also called on Hong Kong citizens to turn on the protesters by refusing to accept their promotional materials and opposing disruptions to public transport.

The council is struggling to contain the ongoing protests, which were sparked in March over the now-withdrawn extradition bill with China, which many feared would have allowed Beijing to silence dissidents.

The anti-government protests have continued and now encompass broader demands around democracy and government accountability.

Police on Monday fired tear gas at protesters after a general strike hit transport and the city's Beijing-backed leader warned its prosperity was at risk.

The amount of violence and property damage has increased in recent protests, with 10 people injured last week when fireworks were shot from a moving car into a crowd of pro-democracy activists.

More than 40 people faced a Hong Kong court last week, charged with rioting for their role in a recent protest that turned violent when thousands of activists clashed with police near Beijing's main representative office in the city.

Fears over military intervention

Like the other press conference in the past week, Chinese officials condemned protesters and voiced their support for pro-Beijing Hong Kong leader Carrie Lam, who protesters want to step down.

"We call on people from all walks of life in Hong Kong to unequivocally oppose and resist violence," Mr Yang said on July 29, when he also labelled protesters "evil' and "criminals".

"No civilised sociality under the rule of law would ever allow acts of violence to take place."

There has been growing speculation that the Chinese Government will send in the People's Liberation Army (PLA) to combat the protesters.

When asked during the first press conference under what circumstances PLA could intervene, Mr Yang referred to Hong Kong's mini constitution, known as the Basic Law, which states that the Hong Kong government can ask the PLA garrison in the city to help maintain order.

Legal scholars have described that as a high threshold.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 37 seconds 37 s Chinese forces based in Hong Kong have released a video showing footage of "anti-riot" exercises

On August 1, the PLA's Hong Kong garrison released a video demonstrating anti-riot drills which included troops firing guns and rockets, and of light tanks, attack helicopters and missile launchers.

Protesters hold own press conference

Just before the council spoke to reporters, a group of anonymous protesters — who wore masks to protect their identities — held their own press conference, in which they condemned what they said was the Government's "empty rhetoric".

Many protesters have chosen to hide their identities because they fear official retribution.

Protesters held the inaugural "People's Press Conference" on Tuesday. ( AP: Kin Cheung )

In what they called the inaugural People's Press Conference, they accused police of showing a "total lack of self-discipline", adding some tear gas was fired on residential buildings during clashes across several districts on Monday.

The protesters apologised for inconvenience caused by Monday's general strike which paralysed regular workday operations in the city. Major roads and public transit lines were blocked, while at least 77 flights out of the airport were cancelled.

ABC/wires