HONG KONG, March 20 (Xinhua) -- Hong Kong's Centre of Health Protection (CHP) reported 48 new confirmed COVID-19 cases on Friday, the highest number for a single day since the outbreak of the virus.

A passenger wears a face mask as a precautionary measure against the COVID-19 coronavirus as he travels on the city-linked train to Hong Kong’s international airport on March 19, 2020. (Photo: AFP)

The new cases have brought Hong Kong's total number of confirmed COVID-19 cases to 256.

The 48 newly diagnosed patients, aged between four to 69 years old, include 23 females and 25 males, Head of the CHP's Communicable Disease Branch Chuang Shuk-kwan said at a daily press briefing on Friday afternoon.

Among them, 36 people had overseas travel history during the incubation period, including a four-year-old girl who had traveled to Britain with her father, some members of a tour group to Canada, a female flight attendant who had been to Indonesia and Britain, an athlete who had been to Europe for training, and eight students who were studying in countries such as Britain, Canada and the United States.

The confirmed cases also include a domestic helper who developed symptoms of the disease after arriving in Hong Kong from the Philippines on March 12, and an Australian national who felt unwell during transfer at the Hong Kong airport and was sent to a hospital in Hong Kong.

Among the rest of the new patients, some are close contacts of previously diagnosed cases, and four are related to two chain fitness gyms.

A taxi driver is one of the few patients who had no travel history during the incubation period. Initial investigations show that the driver often picked up passengers at the airport. The CHP will trace possible close contacts of him, Chuang said.

Hong Kong has seen in recent days an increasing number of imported COVID-19 cases as many travelers returned from overseas amid the global pandemic.

With a large number of people expected to arrive at the Hong Kong International Airport from overseas in the coming days, two temporary test centers were established at the AsiaWorld-Expo and the North Lantau Hospital near the airport, and were put into use on Friday morning.

Starting from Friday, people arriving in Hong Kong with upper respiratory symptoms will be sent to the test centers to receive viral tests and wait for the laboratory results.

Linda Yu, chief manager of Hong Kong's Hospital Authority, said at the briefing that as of 3 p.m. local time 33 specimens have been collected from inbound travelers at the test centers and sent to laboratory for tests.