Police have unleashed pepper spray and baton charges at students who have tried to storm Hong Kong's government headquarters, as tensions soared in the third month of pro-democracy protests.
With morning rush hour underway on Monday, fresh scuffles broke out between police and demonstrators at the main Admiralty protest site.
Tearful protesters were forced from the government site and roads were cleared for traffic, but government offices remained closed with the de facto parliament suspended.
Pro-democracy demonstrators clash with police forces in Hong Kong's Admiralty occupation site. (AAP)
Emotions continued to run high with clashes between police and protesters at a shopping arcade near the Admiralty site, with at least one person taken away on a stretcher.
In chaotic scenes overnight, hundreds of protesters wearing helmets and wielding umbrellas spilled into a major road outside the office of Chief Executive Leung Chun-ying as police tried to beat them back with batons and pepper spray.
"I want true democracy!" protesters yelled. "Surround the headquarters. Paralyse the government."
Protesters have been staging mass sit-ins in Hong Kong since late September, demanding free leadership elections for the semi-autonomous Chinese city.
China's communist authorities insist candidates for the 2017 vote must be vetted by a loyalist committee, which the protesters say will ensure the election of a pro-Beijing stooge.
Police said they had made 40 arrests overnight and 11 officers had been injured.
Several protesters were injured in the overnight clashes. One was seen led away by police with a bloodied face, while others were tended to by first-aid volunteers after being fired at with pepper spray.
Protesters wore builders' hard hats and used umbrellas - which have come to symbolise the pro-democracy movement - to shield themselves from the pepper spray.
Police had to dodge helmets and bottles that were lobbed through the air. One officer was carted into the back of an ambulance on a stretcher.
