Police have increased security around Hong Kong and its university campuses as they braced for more violence after sharp clashes overnight with anti-government protesters.

Many subway and rail stations were closed after the protesters blocked commutes and vandalised trains overnight into Wednesday.

Police and protesters battled on multiple fronts overnight at the Chinese University of Hong Kong, with petrol bombs and fires lighting up the night time scene.

A police official warned protesters were carrying out “insane acts” and Hong Kong was on the brink of a total breakdown after more than five months of protests.

“Our society has been pushed to the brink of a total breakdown,” Senior Police Superintendent Kong Wing-heung said late on Tuesday.

Hong Kong Protests
Students take their position outside the Chinese University of Hong Kong (Kin Cheung/AP)

He said Hong Kong’s mass transit system and subway, known as MRT, was under stress from acts of violence and vandalism.

“Masked rioters have lost control and committed insane acts like throwing trash, bicycles and large objects onto MTR tracks, hanging trash on overhead power lines,” he added.

Groups of riot police were deployed around central Hong Kong and its outlying territories to try and contain new violence, even as students at the Chinese University — located in the outskirts of the sprawling metropolis — prepared for new clashes with police.

Many were armed with petrol bombs while some carried bows and arrows.

Hong Kong Protests
Students walk by a fire during a clash with police at the Chinese University in Hong Kong on Tuesday (Kin Cheung/AP)

The university’s student union president, Jacky So, appealed for an injunction with the High Court to ban police from entering the campus without a warrant or the school’s approval.

Police had entered the campus and fired tear gas and used a water cannon late on Tuesday.

The injunction would also block police from using crowd control weapons, such as tear gas and rubber bullets at the university, and a decision is expected late on Wednesday.

The city’s religious leaders have appealed for an end to the violence and called on both police and protesters to show restraint.

“At this very critical point, the people of Hong Kong must unite and say no to violence,” said a statement issued by the leaders of Hong Kong’s six major religious groups.

Hong Kong Protests
Students burn a train inside the Chinese University MTR station in Hong Kong (Kin Cheung/AP)

Recent weeks have been marked by escalating vandalism of shops linked to mainland China and train stations, and assaults by both protesters and pro-Beijing supporters.

On Monday, a police officer drew his gun during a struggle with protesters, shooting one in the abdomen.

In another neighbourhood, a 57-year-old man who was defending China was set on fire after an apparent argument.

Both remained in a critical condition in hospital on Wednesday.

Police have arrested more than 3,500 people since the movement began in June.

The protests began over a proposed law that would have allowed criminal suspects to be extradited to mainland China, where they could face opaque and politically sensitive trials.

Activists saw the bill as another sign of an erosion in Hong Kong’s autonomy and civic freedoms, which China promised would be maintained for 50 years under a “one nation, two systems” principle when the former British colony returned to Chinese control in 1997.