HONG KONG — Protests in Hong Kong, ongoing for more than six months now, have ramped up with heightened tension and a stand-off at Hong Kong Polytechnic University.

Police have tightened their siege of a university campus where hundreds of protesters are trapped. It’s the latest episode in months of protests against growing Chinese control over the semi-autonomous city.

The work week began Monday with multiple protests that disrupted traffic, while schools remained closed because of safety concerns stemming from the latest wave of demonstrations.

The battle for control of the campus of Hong Kong Polytechnic University has been the centre of the most recent developments. For days, protesters have fortified the campus to keep out the police. Now cornered by police, they tried to get out but faced a cordon of officers armed with tear gas and water cannons.

Officers repelled one escape attempt Monday morning with tear gas, driving hundreds of protesters back onto the campus. Later, huge crowds of supporters advanced on foot toward the police from outside the cordon to try to disrupt the police operation.

Senior government officials said they were trying to de-escalate the situation and urged the protesters to peacefully leave the campus and co-operate with police – advice that seemed certain to lead to arrests and therefore strengthened the protesters’ resolve to resist.

While both sides dug in at the campus, protest supporters rallied in nearby districts across Kowloon as they attempted to get close to the police cordon to disrupt the law enforcement operation and help those trapped inside. But they were met at multiple locations by riot police firing tear gas, turning the busy streets teeming with apartment blocks into a battle zone.

The protests started peacefully in early June, sparked by proposed legislation that would have allowed criminal suspects to be extradited to the mainland. But by the time the bill was withdrawn, the protests had hardened and broadened into a resistance movement against the territory’s government and Beijing.

Activists see the extradition bill as an example of Hong Kong’s eroding autonomy under Beijing’s rule since the 1997 handover from colonial power Britain.

As reported in September, after the protests at Hong Kong International Airport and after the government withdrew the extradition bill, Canadian tour operators selling Hong Kong said they were cautiously optimistic that bookings to the city could get back on track.

With these latest tensions, however, some of the images and video coming out of the city and receiving wide play in the news look more like a war zone than the Hong Kong that the travel industry knows and loves as one of the top destinations in Asia, and the world.

With file from The Associated Press