She was referring to the police force’s Major Incident Investigation and Disaster Support System, which was used during the 2003 Sars epidemic for contact tracing and determining areas of high infection risk.

One more Hongkonger infected on Diamond Princess, total at 66

However, Chuang noted that the city was still not experiencing a community outbreak.

Asked what action was being taken in response to the infection scare, the police force said: “In accordance with the epidemic prevention guidelines and recommendations issued by related government departments ... police officers are reminded to maintain social distance and we will release latest information to them in a timely manner.”

The first police officer to contract the coronavirus, a senior constable stationed in North Point and living with his wife in the disciplined staff quarters at Yau Mei Court in Yau Tong, tested positive on Thursday. He had no travel history over the past 14 days and was on leave when he felt unwell on Tuesday.

He is now being treated at United Christian Hospital in Kwun Tong, while his wife and mother-in-law have also been sent to hospital after developing symptoms.

Their staff quarters are near Domain Mall, where a 38-year-old woman working as a cashier at the Super Super Congee & Noodle shop was confirmed to have the coronavirus and hospitalised on Wednesday.

The officer and his family had eaten at the shop previously, but Chuang said it was still unclear whether they had any close contact with the cashier.

“We will try to trace his movements before he showed symptoms, perhaps using his Octopus card records,” she said.

The infected policeman was assigned to the riot squad under the Hong Kong Island regional response contingent, comprising some 40 officers.

A source said members of the squad were not categorised as close contacts, but had been screened for fever when they reported for duty and were required to wear masks. They were also deployed in operations with no public interaction.

All officers at North Point Police Station were required to undergo temperature checks before starting work there from Friday morning, according to another source.

The force had also cleaned and sanitised the station, related facilities and vehicles, as well as the disciplined service quarters at Yau Mei Court.

But the bigger concern was the fallout from the banquet on Tuesday night that the infected constable attended with 59 others, after four of them were sent to hospital with symptoms such as sore throats, runny noses and diarrhoea.

Thirty-six officers at the banquet were on duty at Aberdeen Police Station on February 20 when the constable was confirmed to be infected. Police management said they had immediately suspended them from duty to await quarantine orders.

The other 23 officers who attended the banquet were attached to Commercial Crime Bureau and different districts on the Hong Kong Island.

Police Commissioner Chris Tang Ping-keung and other top brass have come under fire after they were seen in videos clips posted online attending a banquet on Sunday.

Several pro-establishment celebrities such as filmmakers and actors Jackie Chan and Eric Tsang Chi-wai, and veteran singer Alan Tam Wing-lun, were also at the event.

Hong Kong Medical Association president Dr Ho Chung-ping said he did not think it was necessary for the government or the police force to issue guidelines on attending large social gatherings, but stressed the need to exercise caution.

“The association’s advice is still the same – practise social distancing and avoid casual social gatherings. Of course, in the case of the police officer, it was a farewell, which is harder to reschedule,” Ho said. “If you must attend functions such as farewells and weddings, be on high alert and use common sense and wear a surgical mask until you need to eat.”

Police were in the spotlight once again on Friday as small groups of anti-government protesters gathered to mark seven months since a violent mob attack on demonstrators and passengers at Yuen Long MTR station.

This time, in addition to the usual condemnation of police for their failure to prevent the mob attacks last July, protesters broke out champagne and beer to “celebrate” the first coronavirus infection in the force.

There were standoffs and scuffles at small protests in the shopping district of Causeway Bay and the industrial neighbourhoods of Cheung Sha Wan and Kwun Tong, each of which drew a few dozen participants.

In Times Square in Causeway Bay, a handful of pro-Beijing supporters with a Chinese flag argued and scuffled briefly with protesters before police arrived.

“Any organisation that has attracted so much hate to the point that someone would take pleasure in its members getting a disease must surely reflect on its conduct,” said Ray Wong Cheuk-hei, a waiter in the neighbourhood.

Lam Chi-wai, chairman of the Junior Police Officers’ Association, said the protesters’ “undignified and inhumane” remarks did not even warrant his condemnation.

Health authorities were also experiencing difficulty tracing the contacts of a 58-year-old taxi driver who was confirmed as the city’s 68th case.

The taxi driver had a fever for two weeks, but carried on working, prompting authorities to look for all those who had boarded his vehicle – licence number JW9897 – between January 25 and February 16.

The driver recalled taking passengers to shopping malls and picking up fares from border crossings such as Lok Ma Chau, Shenzhen Bay Port and the Hong Kong-Macau-Zhuhai Bridge, Chuang said.