Lam, who returned to the city on Saturday morning following a week’s visit to Davos, Switzerland for the World Economic Forum, also rebutted mounting criticism that her government had been slow to react in her absence. As of Friday, five confirmed cases of the coronavirus infection had been identified in Hong Kong, along with 108 suspected cases. All patients had been to Wuhan, the epicentre of the outbreak in mainland China.

“There has been no case of waiting for me to get back,” Lam said. “Even when I was in Davos I never stopped liaising with Secretary for Health Sophia Chan and Chief Secretary Matthew Cheung.”

Lam said the new package of measures was introduced because the situation had reached a “critical point”, two days after the city’s first confirmed case.

The government ruled out shutting the border with mainland China, with Lam saying it would be “inappropriate and impractical” to shut down all ports linked to the mainland.

But a labour union representing medical staff said public doctors had threatened to strike if the government refused to close the border.

Lam appealed to the group and called for unity.

“Maybe we have become used to more radical moves in the past few months, but I hope medical staff will not resort to a confrontational approach to fight for their cause,” she said.

Lam confirmed an earlier Post report that schools in the city would remain closed for an extra two weeks. All local and ESF kindergartens, primary and secondary schools in the city will now restart classes on February 17.

The chief executive said health declaration forms would be extended to all entry points into Hong Kong, including the border crossings at Lo Wu and Lok Ma Chau. There would also be temperature checks for outgoing travellers, with priority given to those going to Shenzhen or Macau.

“A false declaration will be punishable by six months in prison or a fine of HK$5,000,” Lam said.

Lam, when challenged on supply and rising prices of masks in Hong Kong, said she had written to the State Council to ask for necessary cooperation.

“The supply of masks is intense, especially during the Lunar New Year,” she said. “We have contacted some suppliers and Hong Kong businesses, who can find supplies from outside the city. The government will also source for masks and [find ways] to settle the demand.

“Some mainland factories may want to increase supplies to Hong Kong and we hope these could be shipped to the city.”

Standard Chartered Marathon confirmed the cancellation of the race on its Facebook page, with about 70,000 participants affected.

“To support the government’s epidemic prevention efforts, the organiser has decided to cancel the Standard Chartered Hong Kong Marathon originally scheduled for February 8 and 9,” it said, adding all entry fees would be fully refunded.

Four medical experts from the University of Hong Kong and Chinese University, including Gabriel Leung, Keiji Fukuda, Yuen Kwok-yung and David Hui Shu-cheong, were named on an advisory group that would directly report to Lam.

Leung, dean of medicine at HKU, warned the virality of the new coronavirus was “no weaker” than [severe acute respiratory syndrome] Sars in 2003.

“There is no sign of a local outbreak in Hong Kong, only imported cases,” Leung said. “Any foreign cases should be contained to stop them from infecting others through close contact.”

Top microbiologist Yuen, also from HKU, on Saturday warned the new coronavirus could be highly infectious and this was the last window to stop the outbreak at the border.

“Hong Kong or Macau or other world cities could easily become another Wuhan or another 2003 Hong Kong,” Yuen said in an online message, referring to the Sars outbreak in 2003 that killed almost 300 people, including eight medical staff.

According to the MTR Corporation, two high-speed trains a day – one coming from Beijing and one from Tianjin – would pass through Wuhan on their way to Hong Kong via Shenzhen.

The railway giant said on Thursday the trains would stop only to allow passengers to get off.

There had also been no flights from Wuhan to Hong Kong since the mainland city was put on a lockdown on Thursday morning.

Director of Health Dr Constance Chan Hon-yee said it would look to set up a digital declaration health notification system. A public housing estate, Fai Ming Estate, in Fanling would also be the fallback site for quarantined patients or doctors, Chan said.

Pro-democracy lawmakers called on the government to take more decisive measures, including barring mainland Chinese travellers from entering Hong Kong, especially those with fever.

Civic Party lawmaker Dennis Kwok said the government could invoke powers under the Prevention and Control of Disease Ordinance to facilitate such a move.

“The government has all the powers under the existing law to deal with all these situations,” Kwok said.

Pan-democrats also said special arrangements should be made to allow Hong Kong residents to return from the mainland, but that their health should be monitored.

Social welfare sector lawmaker Shiu Ka-chun questioned why the measures were only deployed upon Lam’s return.

“Are we waiting for her to take credit?” Shiu said.

Kwok also called on the government to scrap its mask ban in the light of the virus reaching Hong Kong.

Lam had addressed the mask ban in her earlier press conference, saying her administration would continue its appeal against a local court ruling in October that it was unconstitutional.

Under the ban, a “pre-existing medical or health reason” allows a person to wear a mask.

Meanwhile, Macau officials announced on Friday morning that the Lunar New Year holiday should be extended by a week for all schools except higher institutions until February 10, as it also urged private institutions to follow similar arrangements. Some 10 higher education institutions also said they would extend the holiday until February 11.