HONG KONG - Health authorities in Hong Kong reported 25 new coronavirus cases on Wednesday (March 18), the highest in a single day.

Most involved people who returned from abroad, triggering fears that transmission would escalate.

Almost all but one of the 14 first confirmed cases were imported.

Of those who tested positive preliminarily, all had come back from overseas. Of this group, three were students who returned from the United Kingdom.

Dozens of students have rushed back from Europe and the US to Hong Kong ahead of tougher measures.

From Thursday (March 19), anyone entering Hong Kong will have to undergo a compulsory quarantine of 14 days. This will last for three months, health authorities said. Anyone who breaches the quarantine requirement can be fined up to HK$25,000 (S$4,600) and jailed for six months.

Hong Kong's total confirmed cases is now 192, with four deaths.

The authorities say they are looking into ways to strengthen detection and containment measures, including taking saliva samples from people who enter the territory.

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The surge in imported cases has struck fear in the community, driving health experts and lawmakers to urge the government to ban non-Hong Kong residents from entering the city.

On Wednesday, the chief of Hong Kong University's centre for infection Ho Pak Leung said the next two weeks will be a "critical period" in the city's fight against the pandemic.

He pushed for aggressive measures to contain the spread of the virus, such as an entry ban on non-Hong Kong residents, as well as banning people who refuse to wear face masks from public transport and lifts.