The government on Wednesday sealed off West Terrace at Sai Wan Estate for overnight coronavirus testing.
The Kennedy Town residential block had already been under lockdown last week as part of the restriction-testing declaration exercise that covered the entire estate.
Health authorities said they've found 23 infections from West Terrace, including a staff member of Sky Cuisine restaurant in Sheung Wan which has emerged as a coronavirus cluster.
"Having reviewed a basket of factors, including the viral load in sewage, the information of relevant positive cases, and other circumstantial factors, and conducted a risk assessment, the government decided to make another 'restriction-testing declaration' for West Terrace of Sai Wan Estate following last week's exercise," a statement says.
Residents there are required to get tested for Covid, with the operation expected to end at 10am on Thursday.
Authorities have cordoned off two other residential buildings for Covid screening. They are King Tai House at On Tai Estate in Kwun Tong and Ka Yiu House at Ka Shing Court in Fanling.
Earlier, officials found three positive and two undetermined cases after testing around 1,000 residents of Ping Wah House at Lok Wah North Estate in Kwun Tong.