An anti-government protester walks past a fire on a bridge at one of the entrance that leads into the Hong Kong Polytechnic University in the Hung Hom district early Tuesday. (AFP)

Hong Kong’s chief executive said Tuesday that protesters occupying a city center university had to surrender if the three-day standoff was to be resolved peacefully.

In her first public comments on the siege at Hong Kong Polytechnic University (PolyU), Carrie Lam said she believed around 100 people remained at the campus, surrounded by police who were trying to quell the unrest.

“This objective could only be achieved with the full cooperation of the protesters, including of course the rioters that they have to stop violence, give up the weapons and come out peacefully and take the instructions from the police,” she told a press conference.

Hundreds of mainly young protesters took over the campus at the weekend, holding off police assaults with a barrage of Molotov cocktails, bricks and arrows, in the most extreme expression of a popular protest movement that is now in its sixth month.

The university siege has become a battle of wills between Hong Kong’s stretched police force and the constantly innovating protest movement.

Late Monday, dozens of black-clad protesters on a footbridge slithered down ropes several meters to a road below, where they were whisked away on motorbikes.

In an apparently coordinated effort, tens of thousands of Hong Kongers streamed towards the PolyU campus to break the siege, as clashes simultaneously raged with police nearby in Kowloon.

Several dozen people remained on the campus, one protester told AFP, although a number of minors were allowed to leave after negotiations with lawmakers. Relatives held anxious vigil Tuesday as police vowed to arrest everyone on the campus.

One woman, who gave her surname as Cheung, said she had spent Monday night in a park near a police cordon as she waited for news of her adult son, who she said came to the campus as a first aider.

“I was very, very worried, worried his life could be in danger. He’s scared. He’s scared about being arrested by the cops,” she said.

A new phase of violence and drama began last week and has led to chaos throughout the semi-autonomous city of 7.5 million people, with schools closed, train lines disrupted and major roads blocked by barricades.

China has refused to budge on any of the protesters’ demands, and warned it will not tolerate dissent in the financial center.

A brief appearance by Chinese soldiers on Hong Kong’s streets over the weekend — supposedly to clean up debris — fueled concerns that Beijing could intervene militarily.