HONG KONG (Reuters) -- Police fired tear gas to disperse hundreds of anti-government protesters in Hong Kong on Sunday after violent clashes a day earlier, and Beijing said it would not let the situation persist.
The Chinese-controlled city has been rocked by months of protests against a proposed bill to allow people to be extradited to stand trial in mainland China and they have now grown into calls for greater democracy.
A general strike aimed at bringing the city, an Asian financial hub, to a halt is planned for Monday.
After the peaceful demonstrations finished, hundreds of masked 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.
Police fired tear gas to disperse 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 began a march towards China's Liaison Office which has been a flashpoint at previous protests.
Police said the protesters were "participating in an unathorised assembly", similar to Saturday when they fired multiple tear gas rounds in confrontations with black-clad activists in the Kowloon area.
Police said they had arrested more than 20 people for offences overnight including unlawful assembly and assault. The protests have become the most serious political crisis in Hong Kong since it returned to Chinese rule 22 years ago after being governed by Britain since 1842. China's official news agency Xinhua said on Sunday: "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."
During the day protesters had marched brandishing coloured leaflets, called for a mass strike across Hong Kong on Monday and shouted "Restore Hong Kong" and "Revolution of our time."
"We're trying to tell the government to (withdraw) the extradition bill and to police to stop the investigations and the violence," said Gabriel Lee, a 21-year-old technology student.
Lee said what made him most angry was that the government was not responding to any of the protesters' demands or examining the police violence.
What started as an angry response to the now suspended extradition bill, has expanded to demands for greater democracy and the resignation of leader Carrie Lam.
"Even if Carrie Lam resigns, its still not resolved. It's all about the Communist Party, the Chinese government," said Angie, a 24-year-old working for a non-government organisation.
Protesters on Saturday set fires in the streets, outside a police station and in rubbish bins, and blocked the entrance to the Cross-Harbour Tunnel linking Hong Kong island and the Kowloon peninsula.
Shops in the tourist and commercial area Nathan Road, normally packed on a Saturday, were shuttered including 7-11 convenience stores, jewellery chain Chow Tai Fook and watch brands Rolex and Tudor.
Thousands of civil servants joined in the anti-government protests on Friday for the first time since they started in June, defying a warning from authorities to remain politically neutral.
The protests have adapted rapidly since the start of June with the movement spreading from the Admiralty area, where the legislative council is located, across to the whole city for the first time.
Previous protests have also targeted mainland visitors to try and make them understand the situation in what is officially termed a Special Administrative Region of China.
Young people have mostly been at the forefront of the protests, infuriated with broader problems including sky-high living costs and what they see as an unfair housing policy skewed towards the rich.
However, the demonstrations have seen people of all ages, including families and the elderly take part.
The protests mark the biggest popular challenge to Chinese leader Xi Jinping since he took office in 2012.
Hong Kong has been allowed to retain extensive freedoms, such as an independent judiciary but many residents see the extradition bill as the latest step in a relentless march toward mainland control.
Months of demonstrations are taking a growing toll on the city's economy, as local shoppers and tourists avoid parts of one of the world's most famous shopping destinations.
Matthew Wang, a 22-year-old marketing executive for a multinational corporation, said that the government was "encouraging people to become more radical to affect decision making because they are not addressing any of the demands."