More than 20 protesters inside a Hong Kong university campus have surrendered to police, as the city’s largest pro-Beijing political party urged voters to “kick out the black force” in upcoming elections seen as a key gauge of public support for anti-government demonstrations.

At least 22 people left Hong Kong Polytechnic University, which has been ringed by riot police for days, as the campus siege edged closer to an end.

Ten protesters walked out together on Thursday and were escorted to a police post outside the campus, while three were carried out on stretchers and four were taken in wheelchairs.

Five other students, believed to be minors, came out with their parents and were allowed to leave after police took their details.

It is unclear how many protesters were left behind. They are the remnants of a much larger group that occupied the campus after battling police over the weekend.

Some 1,000 protesters have either surrendered or been stopped while trying to flee.

The city’s largest political party slammed the flare-up in violence in the past week and urged some 4.1 million voters to use the ballot box this Sunday to reject the “black force” that it said has thrown the semi-autonomous Chinese territory into unprecedented turmoil since June.

Starry Lee, who heads the Democratic Alliance for the Betterment and Progress of Hong Kong, said “The black force say they want to fight for freedom but now people cannot even express their views freely. We have even been stripped of our right to go to school and work.”

Ms Lee and some party candidates kicked black footballs as a symbolic gesture to banish the black-clad protesters.

The party is contesting 181 of the 452 district council seats, a low-level neighbourhood election held every four years.

For the first time, all the seats will be contested and a huge win by the pro-democracy bloc could bolster the legitimacy of the protest movement.

Protesters, who believe mainland China is increasing its control over the territory, are demanding fully democratic elections and an independent probe into alleged police brutality against demonstrators.

The government, which rejected the demands, has warned the polls could be delayed if violence persists and transport links are disrupted.

Earlier on Thursday, there were long queues and delays at some subway stations. Some stations remained shut and protesters tried to block train doors from closing, but the disruption was relatively minor.

Ms Lee said the party’s candidates have faced threats and some have even been beaten up — but they are ready for a “tough battle”.

At a campaign event, she said: “We believe that if we are united and if everyone comes out to vote, Hong Kong can be restored and violence can be stopped.”

More than 5,000 people have been arrested since the protests started in June over a now-abandoned extradition Bill that would have allowed criminal suspects to be sent to mainland China for trial.

The protests have since swelled into an anti-China movement as many fear a loss of freedoms guaranteed to the former British colony when it returned to Chinese control in 1997.–PA