A Hong Kong police officer has shot a protester in the chest during clashes that were broadcast live on Facebook.

Key points: Several live broadcasts show a police officer shooting a protester at close range

Several live broadcasts show a police officer shooting a protester at close range The protester was reportedly trying to block a road in Sai Wan Ho

The protester was reportedly trying to block a road in Sai Wan Ho It's been the 24th straight weekend of anti-government protests in Hong Kong

Hong Kong police opened fire on protesters as chaos erupted across the city on Monday morning, local media reported.

The protester was reportedly trying to block a road in Sai Wan Ho when he was shot with a live round.

The Hospital Authority said a man suspected to have been injured in the clash was in a critical condition and undergoing an operation.

Police had fired live rounds at protesters on the eastern side of Hong Kong island, local media reported.

In two separate incidents, a man was doused in petrol and set alight during an argument on a footbridge in Hong Kong, while a police officer rode a motorcycle into a group of protesters.

The video shows the man being doused in what appears to be petrol before he is set alight. ( Supplied: Twitter )

Video posted on social media showed the man yelling at a group of people before someone splashed him with petrol and held a lighter to his shirt.

The man was engulfed in flames before ripping off his shirt and running away.

The hospital authority said a man had been admitted with severe burns and was in critical condition.

In footage posted on Twitter, a police officer can be seen riding their motorbike towards a black-clad protester, who narrowly avoids being hit. The police officer then drives into a group of protesters walking down a road.

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Police said in a statement radical protesters had set up barricades at multiple locations across the city and officers warned the demonstrators to "stop their illegal acts immediately".

However, police did not comment on the shooting.

Protesters are reportedly expected to set up barricades on major roads while disrupting the operation of the railway.

It comes a day after officers fired tear gas to break up rallies as activists blocked roads and trashed shopping malls in the financial hub.

The rail station closed on Sunday in the central town of Sha Tin amid scuffles between police and protesters, who have planned disruptions at shopping centres throughout the territory.

Anson Yip, a 36-year-old Sai Wan Ho resident, said protesters were throwing rubbish to create a road block when police ran to the scene.

Police point weapons at protesters in a shopping mall at Tsuen Wan. ( AP: Kin Cheung )

"They didn't fight and the police ran and directly shot. There was three sounds, like 'pam, pam, pam'," they said.

Police later fired tear gas in the same area where the protester was shot.

Protesters formed a barricade of polystyrene boxes around the bloodstain next to a pedestrian crossing after police forensic teams left the scene.

A 24-year-old man, one of several office workers gathered at the scene after the shooting, said: "When I arrived the road was blocked and people were yelling at the police, calling them murderers."

The man only gave his surname, Wing.

Students fight back

Demonstrators blocked subway lines and roads during the morning commute as police responded with tear gas. ( AP )

Violence flared at several university campuses throughout the morning as news of the latest shooting spread, with witnesses reporting tense standoffs between students, protesters and police.

All classes were cancelled.

Police fired tear gas and rubber bullets, while student protesters hurled homemade petrol bombs at police.

Students set fire to debris at the Polytechnic University on the Kowloon side of Victoria Harbour.

"I am worried about my safety but I will still come out," said Anson, a 20-year-old student at Hong Kong Polytechnic University who only gave his first name.

"I am willing to sacrifice my life for Hong Kong," he said.

It has been the 24th straight weekend of anti-government protests in Hong Kong, as demonstrators showed their fury over what they described as police brutality.

Last weekend, anti-government protesters crowded into a shopping mall when a man slashed people with a knife and bit off part of a politician's ear.

Hong Kong is in the sixth month of protests that began in June over a proposed extradition law and have expanded to include demands for greater democracy and other grievances.

Hongkongers are furious at what they see as police brutality and meddling by Beijing in the former British colony's freedoms, guaranteed by the "one country, two systems" formula in place since it returned to Chinese rule in 1997.

China denies interfering in Hong Kong and has blamed Western countries for stirring up trouble.

ABC/Wires