The boisterous crowd broke into euphoric cheers as police were forced to retreat in the gritty district of Mong Kok rather than risk escalating confrontations, as tensions flared through to the early hours of Saturday. Police use of batons and pepper spray failed to curtail as many as 9000 demonstrators, according to police estimates.

Although protesters were unarmed, as has been the case throughout the unprecedented civil disobedience movement that has ensnarled city traffic for almost three weeks, police reported 15 injuries to its officers, and at least 26 arrests. The number of injuries to protesters was not released, but volunteer first-aiders said they treated at least 50 for the effects of pepper spray and mostly minor head injuries.

The re-occupation of Mong Kok was a response to a pre-dawn police operation on Friday, when dozens of officers cleared tents and barricades at the often volatile Kowloon offshoot to the main protest site outside government headquarters. Demonstrators have been calling for a democratic ballot to elect the city's leader, and for the current incumbent, Leung Chun-ying, to step down.

The swell of demonstrations on Friday night defied a recent trend of dwindling numbers at protest sites, with some exhausted protesters growing discouraged by an apparent lack of direction and progress toward their cause.

Most protest sites are quiet during the day but build in the evenings. Hundreds of tents line the main protest site outside government headquarters in Admiralty, which remains untouched by police.

"We understand everyone has to work and people will feel tired, but people will come out when we need them, like tonight," said Kelvin Yam, a 24-year-old protester at Mong Kok. "When we feel weak the people come out and we feel strong again."

Wary of another dawn raid from police, most protesters stayed through the night, occupying long stretches of Nathan Road, the main neon-lit shopping strip lined with jewellers, banks and apartment towers. Hundreds of protesters also converged at Lung Wo Road outside the chief executive office, which has emerged as another flashpoint in recent days.

The renewed conflict has again cast doubt on the ability of talks to proceed between the government and the student organisations leading the protests. After previous abortive attempts at dialogue, government representatives and the Federation of Students were due to meet on Tuesday.

Hong Kong chief executive Leung Chun-ying has insisted the dialogue would proceed only on the basis that students recognise that Beijing would not concede ground on its decision to reject public nomination at the next chief executive election in 2017. The protests sweeping Hong Kong were triggered by a decision by China's national legislature to effectively give itself a veto over who can run for the city's top leader. Many residents have been further angered by police treatment of demonstrators.

Occupy Central, another prominent group behind the protest movement, called for restraint from both sides, while accusing the government of deliberately provoking protesters by clearing protest sites, which "will only push the resentment from occupiers and citizens who support them into a vicious circle".

"We call on the government to conduct talks with the students as soon as possible and to create the space to ease the deadlock," it said in a statement on Saturday.

Earlier on Friday, Hong Kong's Legislative Council's house committee voted down two requests from pan-democrat politicians for an inquiry into the multimillion-dollar payments made to Mr Leung by Australian firm UGL, relating to the sale of property business DTZ before he was elected as chief executive in 2012.