Hong Kong’s government said violence and illegal protests were pushing the city to an “extremely dangerous edge”, as police fired multiple rounds of tear gas to disperse hundreds of anti-government protesters on Sunday and Beijing said it would not let the situation persist.

The Chinese-controlled city, an Asian financial hub, has been rocked by months of protests that began against a proposed bill to allow people to be extradited to stand trial in mainland China and have developed into calls for greater democracy.

A general strike aimed at bringing the city to a halt is planned for Monday. Many flight departures were shown as being cancelled on Monday and a source and media reports said this was due to aviation workers planning to strike.

Late on Sunday, hundreds of masked protesters blocked major roads, spray-painted traffic lights, started fires and prevented transport from entering the Cross-Harbour Tunnel linking Hong Kong island and the Kowloon peninsula.

“We sprayed the traffic lights because we don’t want traffic to work tomorrow and we don’t want citizens to go to work,” said one protester who was clad from head to toe in black.

Riot police confronted the protesters, who have adopted flash tactics, shifting quickly from place to place to evade capture and using online platforms such as Telegram to direct hundreds of people.

In a strongly worded statement late on Sunday the government said the events of the day showed once again that violence and illegal protests were spreading and pushing Hong Kong towards what it called “the extremely dangerous edge”.

Such acts had already gone far beyond the limits of peaceful and rational protests and would harm Hong Kong’s society and economic livelihood, it said.

After the peaceful demonstrations finished earlier on Sunday, protesters blocked roads in the town of Tseung Kwan O in the New Territories, set up barricades and hurled hard objects including bricks at a police station.

The police fired tear gas to disperse hundreds of protesters after a separate rally in the island’s Western district where thousands of people gathered to urge authorities to listen to public demands.

Protesters had begun a march towards China’s Liaison Office, which has been a flashpoint at previous protests.

China’s official news agency Xinhua said on Sunday: “The central government will not sit idly by and let this situation continue. We firmly believe that Hong Kong will be able to overcome the difficulties and challenges ahead.”

Later on Sunday night, police fired tear gas in the shopping area of Causeway Bay to dispel protesters, forcing stores and popular shopping malls including Times Square to close early.