Thousands of Hong Kong pro-democracy activists have forced the temporary closure of government headquarters after clashing with police, defying orders to retreat after more than two months of sustained protests.
Hong Kong leader Leung Chun-ying said police had been very tolerant but would now take "resolute action", suggesting that patience may have finally run dry.
Chaos erupted as commuters made their way to work, with hundreds of protesters surrounding Admiralty Centre, which houses offices and retail outlets, in a stand-off with police.
The central government offices and the legislature were forced to close in the morning, as were scores of shops.
The latest flare-up, during which police charged protesters with batons and pepper spray, underscored the frustration of protesters at Beijing’s refusal to budge on electoral reforms and grant greater democracy to the former British colony.
“Some people have mistaken the police’s tolerance for weakness,” Mr Leung told reporters. “I call for students who are planning to return to the occupation sites tonight not to do so.”
He did not respond when asked if police would clear the sites on Monday.
The democracy movement represents one of the biggest threats for China's Communist Party leadership since Beijing's bloody 1989 crackdown on pro-democracy student protests in and around Tiananmen Square.
Hundreds of riot police scattered the crowds in several rounds of heated clashes on Sunday night, forcing protesters back with pepper spray and batons.
Scores of volunteer medics attended to numerous injured, some who lay unconscious and others with blood streaming from head gashes. Police said at least 40 arrests were made.
As police tackled the running battles in Admiralty, tensions escalated across the harbour in the working-class district of Mong Kok.
Mong Kok had been the scene of violent clashes in recent weeks before the clearance of a large protest encampment from a major area there last Wednesday.
The unrest came as British lawmakers said they had been told by the Chinese Embassy they would not be allowed to enter Hong Kong as part of an inquiry into Britain’s relations with its former colony and progress towards democracy.
Chinese Foreign Ministry spokeswoman Hua Chunying said Beijing had told Britain it was opposed to the inquiry and that as China had responsibility for Hong Kong's foreign affairs, it had every right to decide who to let into the city.
Hong Kong returned to Chinese rule in 1997 under a “one country, two systems” formula that gave it some autonomy from the mainland and an undated promise of universal suffrage.
The protesters are demanding free elections for the city’s next leader in 2017 rather than the vote between pre-screened candidates that Beijing has said it would allow.
The Hong Kong rallies drew more than 100,000 on to the streets at their peak. Numbers have since dwindled and public support for the movement has waned. Reuters