The protesters planned to rehearse and sing the national anthem on Sunday night, before staging a protest at 6.30am on Monday to block the official gala.

By Saturday, police had started to close off the roads surrounding the exhibition centre from vehicle access and would keep them closed until after the flag-raising ceremony.

A government source said the authorities were preparing for a range of scenarios.

“Up to now, our goal is to hold the flag-raising ceremony in Golden Bauhinia Square and the cocktail reception at Hong Kong Conference and Convention Centre,” the source said.

At a press conference on Saturday, police officials declined to answer whether they had requested that the exhibition centre be closed over security concerns.

“We have received information that someone would disturb the flag-raising ceremony, therefore the police have made some appropriate arrangements at Wan Chai and the convention centre after conducting risk assessments. But it is inappropriate for me to disclose those operational details here,” said San Tsz-kin, the deputy district commander for Central district.

so officers could help make arrangements for a protest area that would be set up outside the Renaissance Hong Kong Harbour View Hotel.

When he was asked if the police would handle the Monday rally differently due to recent clashes between police and protesters, San said officers would be there to help protesters.

“Police and protesters do not stand on opposing sides. In fact, we are partners. We are here to help assist them conduct events in a safe and orderly manner,” he said.

“Our overall principle is that we will facilitate all peaceful and lawful public events. This is our philosophy and in the future we will be following the same principle.”

Hong Kong Dog Rescue, which has a booth at the exhibition centre for the pet expo expressed disappointment with the early closure of their three-day event. An announcement on the group’s Facebook page said “There will be no Pet Expo tomorrow (Sunday) due to “government’s orders.”

The group continued: “Very unfortunate news for us as a charity trying to raise funds and for pet owners and suppliers in Hong Kong who are now affected by a government showing it doesn’t care.”

Exhibitors were told the expo was to end on Sunday but they could not pack up until Tuesday because of security reasons. Some said this would mean leaving valuable stock unattended for days.

“I’m extremely annoyed. We paid for three days and then told we could only do business for two. Is there a reason why they stopped us doing business? It makes no sense, I see no protesters,” said Lyman Chan, 46, an employee of wholesale pet business V&S.

“If you had a store and the police blocked the whole street suddenly and asked you to close, how would you feel?”

Billy Chan, the 32-year-old manager of online pet store Espetsso, was more sanguine about the announcement and supported the organisers move to close early.

He said he was personally informed by organisers of the early closure at 4pm. He said his store spent HK$20,000 (US$2,559) to decorate his booth on top of a HK$40,000 fee to be an exhibitor across the three days.

“We haven’t been told yet, but I’m hoping [to be compensated],” said Chan.

The pet expo will end at 9pm on Saturday.