Hong Kong police warn of 'live fire' as campus protest siege deepens

Hong Kong police Monday warned for the first time in months of unrest that they may use "live rounds" after pro-democracy protesters fired arrows and threw petrol bombs at officers at a besieged university campus, as the crisis engulfing the city sharply escalated.

Protests have tremored through the global financial hub since June, with many in the city of 7.5 million people venting fury at eroding freedoms under Chinese rule.

China has repeatedly warned that it will not tolerate the dissent, and there have been concerns that Beijing could send in troops to put an end to the spiralling unrest.

A day of intense, rolling clashes on Sunday, which saw a police officer struck in the leg by an arrow and protesters meet police tear gas with volleys of petrol bombs, worsened as night fell.

Clashes spilled across Kowloon, with the epicentre around the Hong Kong Polytechnic University (PolyU), where scores of defiant demonstrators set large fires to prevent police from conducting a threatened raid on the campus.

They hunkered down under umbrellas from occasional fire from water cannon and hurled Molotov cocktails at an armoured police vehicle, leaving it ablaze on a flyover near the campus.

Police declared the campus a "riot" scene -- a rioting conviction carries up to 10 years in jail -- and blocked exits as spokesman Louis Lau issued a stark warning in a Facebook live broadcast.

"I hereby warn rioters not to use petrol bombs, arrows, cars or any deadly weapons to attack police officers," he said.

"If they continue such dangerous actions, we would have no choice but to use the minimum force necessary, including live rounds, to fire back." Three protesters have been shot by police in the unrelenting months of protests, but all in scuffles as chaotic street clashes played out -- and without a sweeping warning being given by a force which overwhelmingly depends on tear gas, water cannon and rubber bullets.

Fear gripped protesters still trapped on Monday inside the campus -- whose occupation is a twist in tactics by a leaderless movement so far defined by its fluid, unpredictable nature.

"I feel scared. There's no way out, all I can do is fight to the end," said one protester joining the barricade in front of the university building.

Owen Li, a PolyU council member and student, said "panic" had taken hold of the estimated few hundred protesters who remained.

"Many friends feel helpless... we appeal to all of society to come out and help us."