Dozens of people are under investigation for trying to leave Hong Kong before completing their quarantine for the coronavirus, while four have been jailed for breaking the orders, according to the city’s top health official.

Secretary for Food and Health Sophia Chan Siu-chee also revealed on Wednesday that the Department of Health had sent more than 173,000 into quarantine, as of Monday, and officers had made about 390,000 telephone or video calls to check up on those confined to official centres, their homes, or chosen accommodation.

Opposition lawmaker Kwok Ka-ki said officers should have contacted those subject to the orders more often, but pro-establishment legislator Regina Ip Lau Suk-yee said the data suggested the city’s health measures had been successful.

Chan also disclosed that eight people were suspected of providing false or misleading information, referring to the now-criminalised act of concealing medical or travel history from health workers.

Referring to the 56 people suspected of trying to flee Hong Kong in breach of 14-day quarantine orders, Chan said: “The [Department of Health] and police will continue investigations into the cases concerned and gather more evidence for consideration by the Department of Justice for making prosecutions.”

The quarantine figures were revealed in written responses to lawmakers’ questions after Hong Kong marked 100 days of the coronavirus crisis.

Hong Kong has recorded either zero or just a handful of new infections a day for more than two weeks, with the city total standing at 1,040, including four related deaths.

As part of its emergency response to the crisis, the city quarantined from February those entering from mainland China, an earlier epicentre of the virus.

It extended the isolation measure a month later to all arrivals from overseas, when the coronavirus took hold of Europe and America.

Those in breach of the orders face prosecution which could result in a HK$25,000 (US$3,225) fine and up to six months in jail.

Kwok, of the Civic Party, accused the government of failing to properly check up on those in quarantine, adding that infections breaking out at Hong Kong’s bars and a Buddhist temple reflected that negligence.

But Ip said the improving Covid-19 situation in the city had shown the government had “done a pretty good job”.

Some 82,000 wristbands were handed to those under home quarantine. Meanwhile, more than 80,000 people were told to share their real-time location with officials through mobile software, Chan said.

Four people had been prosecuted for breaking quarantine and were jailed for terms ranging from 10 days to three months, she said.

The heaviest sentence was handed in late March to a homeless 31-year-old man, who lied to health officers that he would stay at a youth hostel. An Indian businessman received a four-week sentence after being intercepted at the border.