HONG KONG (Reuters) -- Police fired tear gas at pro-democracy protesters in Hong Kong's Central financial district and at demonstrators on the other side of the harbour on Tuesday as a senior officer said the unrest had brought the city to "the brink of total breakdown".
The clashes took place a day after police shot a protester at close range and a man was doused with petrol and set on fire in some of the worst violence in the Chinese-ruled city in decades.
More than 1,000 protesters, many wearing office clothes and face masks, rallied in Central for a second day during lunch hour, blocking roads below some of the city's tallest skyscrapers and most expensive real estate.
After they had dispersed, police fired tear gas at the remaining protesters on old, narrow Pedder Street. Police made more than a dozen arrests, many pinned up on the pavement against the wall of luxury jeweller Tiffany & Co.
Police said masked "rioters" had committed "insane" acts, throwing trash, bicycles and other debris on to metro tracks and overhead power lines, paralysing transport in the former British colony. TV footage showed activists dropping heavy objects from overpasses on to traffic below, just missing a motorcyclist.
"Our society has been pushed to the brink of a total breakdown," Senior Superintendent Kong Wing-cheung told a briefing, referring to the last two days of violence
The demonstrators have been protesting since June against what they believe to be meddling by Beijing in the freedoms guaranteed under the "one country, two systems" formula put in place when the territory returned to China from British rule in 1997. Tough police tactics in response to the unrest have also fuelled anger.
China denies interfering and has blamed Western countries including Britain and the United States for stirring up trouble.
As well as the protests in Central, the heart of the Asian financial hub on Hong Kong island, clashes also erupted in several places on the mainland.
Police fired tear gas at City University in Kowloon Tong and at Chinese University in the New Territories, where protesters threw petrol bombs and bricks at police.
Students in hard hats and gas masks had since morning been barricading City University. Activists, who had home-made shields, stockpiled bricks and petrol and nail bombs on bridges and other approaches.
They overran the campus and smashed up the adjacent Festival Walk shopping mall and set fires, including to a big Christmas tree.
Streets inside and outside the Chinese University campus entrance were littered with bricks, other debris and street fires as police tackled protesters to the ground.
The students were taking part in a heated exchange with the principal when clashes reignited, with police again firing volleys of tear gas and protesters throwing petrol bombs.
Protesters also threw petrol bombs from an overpass on to the highway linking the Northern New Territories with Kowloon, bringing traffic to a standstill in a haze of tear gas smoke.
Several students were wounded in the violence.
Police also fired tear gas in the town of Tai Po, where a truck was set on fire, and in the densely populated Kowloon district of Mong Kok, whose shopping artery Nathan Road has been the scene of many clashes.
Hong Kong leader Carrie Lam said protesters were being selfish and she hoped that universities and schools would urge students not to take part in the demonstrations.
More than 260 people were arrested on Monday, police said, bringing the total number to more than 3,000 since the protests escalated in June. Schools and universities said they would close again on Tuesday.
The United States on Monday condemned "unjustified use of deadly force" in Hong Kong and urged police and civilians alike to de-escalate the situation.
In Beijing, Chinese Foreign Ministry spokesman Geng Shuang urged Britain and the United States not to intrude, saying: "Hong Kong affairs are purely China's internal affairs that allow no foreign interference."
China has a garrison of up to 12,000 troops in Hong Kong who have kept to barracks since 1997 but it has said it will crush any attempts at independence, a demand for a small minority of protesters.
Geng also said the Chinese government firmly supported Lam's administration and the Hong Kong police in maintaining order and protecting citizens' safety.
Yang Guang, spokesman for China's Hong Kong and Macau Affairs Office, said China condemned the dousing of the man with petrol and setting him on fire. He demanded that the person responsible be arrested as soon as possible.
Following Tuesday's violence, the Hong Kong Jockey Club said all off-course betting centres would be closed ahead of Wednesday's racing at Happy Valley, to ensure the safety of our employees and customers.