Just a handful of anti-government protesters remain holed up at a Hong Kong university as a police siege of the campus entered its third day.

Around 100 were left on Tuesday but many of those decided to make attempts to escape and others handing themselves in.

Police say they intercepted 37 protesters who deiced to leave the campus on Tuesday.

Catholic Auxiliary Bishop Joseph Ha entered the campus in the evening to persuade those remaining to depart.

City leader Carrie Lam said 600 people had left the Hong Kong Polytechnic campus, including 200 who are under 18 years old.

Ms Lam said those under 18 would not be immediately arrested but could face charges later.

She added the other 400 who have left have been arrested.

Those arrested could be charged with rioting which carries a prison sentence of up to 10 years.

Police have surrounded the university and are arresting anyone who leaves.

Groups of protesters made several attempts to escape on Monday, including sliding down hoses to waiting motorcycles, but it was not clear if they evaded arrest.

Molotov cocktails are left over at the Hong Kong Polytechnic University campus Credit: Ng Han Guan/AP

“We will use whatever means to continue to persuade and arrange for these remaining protesters to leave the campus as soon as possible so that this whole operation could end in a peaceful manner,” Ms Lam said after a weekly meeting with advisers.

Ms Lam was also asked whether she would seek help from Chinese troops based in Hong Kong, but said her government remains confident it is able to cope with the situation.

Many of those who have escaped the university have had to do so in dramatic fashion including jumping from a height.

A number of parents of protesters staged their own manifestation by sitting on the floor with homemade cards.

They want the government and police to allow their children to leave the university freely as they are fearful they could be harmed.

One parent said: "Our concern is the children. They've become desperate, confused. Ultimately - what do they do? We don't know. What do police do? We don't know.

"That's why we just hope that before tonight, the government and the police can sort this out peacefully.

"And let all the children or the youth come out safely to meet their parents. That's why we're concerned."

After five months, the Hong Kong protest movement has steadily intensified as local and Beijing authorities harden their positions and refuse to make concessions.

Universities - which until recently had not been part of the mass protests - became the latest battleground last week, as protesters occupied several campuses, using petrol bombs and bows and arrows to fend off riot police backed by armoured cars and water cannon.

One member of police staff was shot in the leg with an arrow.

China, which took control of the former British colony in 1997 promising to let it retain considerable autonomy, flexed its muscles, sending troops outside their barracks over the weekend to help clean up debris strewn by protesters to block streets.

Riot police detain a protester at Hong Kong Polytechnic University Credit: Achmad Ibrahim/AP
  • What happened on Monday?

On Monday, China’s ambassador to Britain accused the UK and the US of meddling in the country’s internal affairs and warned that the Chinese government “will not sit on our hands” if the situation in Hong Kong “becomes uncontrollable”.

China also hinted it might overrule the Hong Kong’s high court ruling on Monday to strike down a ban on face masks that was aimed at preventing protesters from hiding their identity to evade arrest.

A statement from the National People’s Congress’s (NPC) Legislative Affairs Commission said the decision does not conform with the territory’s constitution, known as the Basic Law, or decisions by the Congress.

“We are currently studying opinions and suggestions raised by some NPC deputies,” the statement said.

Monday’s ruling said the ban infringes on fundamental rights more than is reasonably necessary.

The ban has been widely disregarded.

Face masks had been banned in Hong Kong but the high court overturned this. Credit: PA
  • What are the protests about?

The protests started peacefully in early June, sparked by proposed legislation that would have allowed criminal suspects to be extradited to mainland China.

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 rule since the 1997 handover from colonial power Britain.