The declaration forms had previously only been required for anyone flying from Wuhan and arriving rail passengers at West Kowloon station.

Chuang Shuk-kwan, head of the communicable diseases branch of the Centre for Health Protection, admitted in an afternoon briefing on Monday that Hong Kong authorities were still making arrangements for the checks.

“We are working with all related departments on the logistics,” she said.

At the airport, no staff or signs showing passengers where to drop their signed health declaration forms, distributed during some flights, were visible. The forms required passengers to declare any symptoms and give their contact details, but did not ask if they had been in Wuhan recently.

Chuang said it was not yet policy for plane passengers to fill in the forms, but some could have been handed out by flight attendants, having been sent to airlines in preparation for the roll-out.

“Except flights from Wuhan [which have stopped already], all other flights have not yet implemented this measure yet,” she said.

A Department of Health spokesman confirmed that airline staff had mistakenly distributed the declaration forms to passengers.

At Lo Wu, the most popular border crossing, which connects with the MTR’s East Rail line, there were no health declaration forms being handed out on Monday afternoon.

To screen arrivals, workers relied on the existing temperature-checking equipment, and officers at immigration counters asking non-residents whether they had visited Hubei in the past 14 days.

One immigration officer, who asked to remain anonymous, criticised the measures as “toothless”.

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“We have no way to identify mainlanders who lie to us, especially if they are coming to seek better medical treatment,” he said.

Despite visitors from Hubei being barred from midnight, the officer said it would be difficult to enforce the ban as they relied on checking the “place of issue” shown on travellers’ permits.

“If they live in Wuhan but their permits were not issued there, we cannot pick them out from the crowds,” he said.

A Hong Kong resident surnamed Cheng was returning to the city with three relatives via Lo Wu after visiting family on the mainland. He said he was surprised the government had not required mainland travellers to sign health declarations.

“I don’t feel that Hong Kong has ramped up measures at the borders,” Cheng said. “If I am a Wuhan resident who suspects I am infected, it’s quite easy to get through the border, as even declaration forms are not required.”

On the mainland side of the border, travellers were only required to fill in health declaration forms provided by the central authorities before entering Hong Kong.

But officers were seen allowing several people without forms to get through immigration on Monday.

No temperature-checking equipment was installed at the mainland border. An officer at a health screening counter admitted she had not barred travellers who reported low fever from entering Hong Kong, but only collected saliva samples from them for examination.

With very few staff at the counters helping travellers to fill in the new forms, a travel agency at the mainland control point was charging HK$6 to borrow a pen and HK$10 for help with the forms.

The Centre for Health Protection said later on Monday evening that mainland authorities had implemented health declaration forms for those entering Hong Kong as part of overall plans to screen those leaving with symptoms.

Hong Kong announced no new coronavirus infections on Monday, leaving the local total at eight.

According to mainland health authorities, more than 2,800 cases have been confirmed there, with 82 deaths – the latest case reported in Beijing. Hubei, with 1,423 confirmed patients, has the most cases among the 30 provinces.

Cases have also been confirmed in Cambodia, Thailand, Vietnam, Singapore, Japan, South Korea, Nepal, Taiwan, Malaysia, France, Australia and the US.

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Dr Chung Kin-lai, the Hospital Authority’s director of quality and safety, said the local patient whose condition had worsened was the second confirmed case, a 56-year-old Hong Kong man who had been to Wuhan to visit relatives.

Other patients remained stable.

Chung added that 69 more people who met the reporting criteria for the coronavirus were admitted to public hospitals in the 24 hours to Monday noon. In total, 110 patients were under isolation.

He also confirmed that people who met the reporting criteria for the new coronavirus would have their medical fees at public hospitals exempted, even if they were not local residents.

“The intention of the measure was to encourage people to be treated,” Chung said. “Treating and isolating the patients would not only benefit them, but also Hongkongers.”

The authority later added that similar arrangements had been implemented for other major infectious diseases in the past, including the outbreak of human swine flu in 2009.

Chung urged patients to be honest in declaring their travel history to medical professionals, saying staff responsible for legal matters were looking into whether there would be liability for those who failed to do so.

Law Cheuk-yiu, vice-chairman of the HA Employees Alliance, said there was also a humanitarian reason for the exemption of medical fees for non-Hongkongers with specific conditions.

“We cannot decline patients treatment or contravene humanitarian grounds by charging exorbitant amounts,” Law said.

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But he also expressed concern that the measure could attract a rush of mainlanders to the city’s hospitals seeking free treatment.

“That’s why we need to close the border [connecting with the mainland],” he said.

Macau had since Monday begun implementing more stringent measures on more than 1,000 visitors from Hubei province.

So far, 144 Hubei visitors who presented no symptoms had left Macau with the assistance of local authorities, while four others who chose to remain were placed in a designated youth hostel for forced quarantine.

Secretary for Food and Health Professor Sophia Chan Siu-chee told a radio programme on Monday that top officials would meet that day to discuss whether further preventive measures would be needed.

Meanwhile, Cathay Pacific revealed on Monday night that it had a passenger who flew from Wuhan to Hong Kong then to Los Angeles and was later confirmed to be infected with the new coronavirus.

The local airline said it had notified health authorities in Hong Kong and the US.

The passenger in question flew from Wuhan to Hong Kong via KA855 on January 20, then took a flight to Los Angeles on CX880 the next day.

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“We are following the health authorities’ prescribed procedures in conducting disinfection of both aircraft and informing the operating crew and employees, as well as assisting efforts in tracing people who were in close contact with the concerned passenger,” a statement from Cathay read.

Just before midnight on Monday, the Department of Health issued a statement advising Hong Kong residents who had been to Hubei in the last 14 days to contact health officers at control points when returning home. They would then be assessed and asked to wear masks immediately even if they have no symptoms, and isolate themselves for two weeks.

The Hospital Authority also urged anyone in Hong Kong who had visited Hubei in the last 14 days to contact the Centre for Health Protection on its hotline at 2125 1122 for advice.

Additional reporting by Danny Lee