Health authorities on Wednesday ordered people who've been to a Chinese restaurant in Tsim Sha Tsui in the past week to get tested for Covid-19, after six customers there came down with the disease.
One patient visited Mr Ming's Chinese Dining on February 18 – the day Hong Kong's social distancing rules were relaxed after the Chinese New Year holiday.
Officials later found out that five preliminary positive cases had also had lunch there on February 19.
Dr Chuang Shuk-kwan of the Centre for Health Protection said as restaurants might not be well-ventilated, the virus might have stayed in the air for some time if an infected customer coughed while eating.
"Although they're separate groups. It is possible that there is a case somewhere during that time in the restaurant and cause the spread. But there are other factors that may be occurring... the staff or the environment," she said.
She said authorities had notified other customers of the restaurant of the infections via the government's LeaveHomeSafe app.
This comes as the city reported 17 new coronavirus infections, 16 of which were locally acquired.
Officials can't trace the source of six infections.
Meanwhile, a secondary school in Ho Man Tin has been told to close for two weeks after a 16-year-old student tested preliminary positive for the virus.
Students and teachers at Yu Chun Keung Memorial College have also been asked to get tested for Covid-19.