• Video report by ITV News Correspondent Debi Edward

Bricks are being laid down at Hong Kong polytechnic university to block police from firing tear gas and entering their place of study.

It comes after some of the fiercest clashes occured where students hurled more than 400 firebombs at police on Tuesday.

Students at the university have barricaded themselves in and have said they are prepared to fight the police.

Chinese President Xi Jinping said ending violence by what he calls "violent criminals" and restoring order is Hong Kong's most pressing task.

ITV News China Correspondent Debi Edward describes what is happening on the ground at the university.

She said: "We are here at the Hong Kong polytechnic university where as you can see students are preparing and planning.

"They have barricaded themselves into this university, creating a fortress of their campus.

"We have seen clashes here from 7am this morning, police are firing teargas around the outskirts and that is why they are been creating these defenses from anything they can kind."

A protester tries to pour water on a fire burning amid debris placed to block a road leading to the Cross-Harbour Tunnel in Hong Kong. Credit: AP

She continues: "They have been making Molotov cocktails and digging up the pavements to gather bricks which they are clearly prepared to use as weapons.

"But also where they have been making these booby-trap passages

"They are anticipating that at some point the police will try and siege their campus because in recent weeks the police have been coming into universities like this and making as many arrests as they can, trying to quell this protest movement.

"The students we have been speaking to have said, they have had enough, they are not going to tolerate it any longer, so they are going to create a battle ground and they say they are prepared to fight the police and keep them away from their place of study."

China's Xinhua News Agency reported the country's leader, Xi Jinping, made comments on Thursday while attending the BRICS summit in Brazil about restoring order in the semi-autonomous region.

Xi was quoted as saying the Chinese government will continue to support Hong Kong leader Carrie Lam, the police and the courts.