“Release the martyrs,” they chanted, referring to those arrested on June 12 after protesters clashed with police who fired tear gas and rubber bullets. Police remained barricaded inside the building throughout the night, once again making no attempt to disperse the protesters.

At one point during the height of the protest, a plainclothes policeman was chased by protesters who tried to grab him as he fled towards the building. He ran onto a balcony before legislators at the scene intervened and the police opened a gate to let the officer in.

In a Facebook post, Senior Superintendent Kong Wing-cheung of the force’s public relations branch said the report room of Wan Chai police station had been closed.

Kong urged protesters not to block the entrances and urged them to remain peaceful and keep order when expressing their views.

In a statement issued after midnight, a government spokesman urged the protesters to disperse.

“It is unacceptable for some protesters to block the roads and surround the police headquarters, seriously affecting the work of the police and causing inconvenience to other members of the public,” he said.

At one entrance to the headquarters, some protesters used umbrellas to confront officers on guard. Television footage showed one protester throw an umbrella in the direction of the officers, while others opened their umbrellas to block their way. Police used shields to fend them off.

Some of the protesters vandalised the building front, defacing the outer walls with obscene and abusive graffiti.

A banner was also hung from a platform on the outside of the building, reading: “Release the protesters.”

At the building’s back gate, dozens of protesters used metal barricades and umbrellas to block anyone from entering or leaving.

Others removed English letters from the “police headquarters” logo on the wall and sprayed Chinese characters reading, “Hong Kong police dog headquarters”.

It was a repeat of the radical action last Friday, when thousands of young protesters took over the roads around police headquarters in an unprecedented 15-hour siege.

Earlier on Wednesday, an estimated 10,000 protesters gathered peacefully in the heart of the financial district to draw attention to their campaign against the extradition bill, ahead of a meeting by world leaders at this weekend’s G20 summit in Osaka, Japan.

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Demonstrators swarmed the public square even before the rally began at 8pm and people streamed in throughout the night. The entrance to a multistorey car park near the site was also jammed with protesters.

After two hours of peaceful protest against the government and its handling of the extradition bill, dozens of protesters occupied parts of the westbound lane of Lung Wo Road near the city’s administrative and legislative headquarters.

By around 10pm police had cordoned off the road and redirected traffic.

During the rally, protesters chanted slogans such as “Withdraw evil extradition law”, “Free Hong Kong” and “We want genuine universal suffrage”, as guest speakers took turns on the stage to address the crowd.

The rally was led by the Civil Human Rights Front, the pro-democracy group that organised two mass marches and other events this month against the bill which would allow the transfer of fugitives to mainland China and other jurisdictions with which Hong Kong has no extradition arrangement.

The front’s leaders said they hoped to draw global attention and support ahead of the Group of 20 world forum on Friday and Saturday.

Chinese President Xi Jinping is expected to attend and hold talks with his US counterpart, Donald Trump.

Beijing said this week it would not allow the Hong Kong issue to be discussed at the Osaka summit and asked foreign countries not to intervene in China’s internal affairs.

Speaking to the protesters, Jimmy Sham Tsz-kit, the convenor of the front, accused the Hong Kong government of making only a “shallow” apology for mishandling the bill and causing conflict.

“If you believe in values like democracy, freedom, human rights and the rule of law, we urge all of you to speak out during the G20 summit and defend our rights together,” he said, appealing to G20 leaders for sympathy.

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To extend its international reach, the front translated Sham’s speech into nine languages – English, Japanese, Spanish, Mandarin, French, German, Indonesian, Korean and Italian.

Lee Cheuk-yan, a former Labour Party lawmaker, said the recent protests had proved the power of the people.

“Even the Chinese Communist Party will be frightened off if we get united,” Lee said. “While we ask for international assistance, we must also stand up for ourselves.”

Secondary school pupil Ivan Wong, 17, who sat his Diploma of Secondary Education exam this year, brought water and other supplies such as masks.

“There aren’t enough protesters tonight. I know the shock impact and effectiveness with the public diminishes every time there is a siege. But we have to persist and keep faith together, because as some have said, no protester thinks a rally can succeed until it actually does.”

Truck driver Tony Chen, 28, said the protest was a marathon rather than a sprint.

“We have to conserve our energy. No violence, no bloodshed, is our goal.”

A 21-year-old student, who did not wish to be named, said he planned to stay the night.

“I’ve decided to come out whenever the crowd size is small,” he said. “I want to do as much as I can.”

But as the movement dragged on, he admitted he was feeling tired.

Some planned to continue on Thursday by marching to Government House or the Department of Justice.

Additional reporting by Ng Kang-chung