Health authorities on Monday said two US Consulate employees had tested preliminary positive for Covid during an overnight "ambush" lockdown in Mid-Levels.
The 40-year-old man and 41-year-old woman live in Dynasty Court. They showed no symptoms and last went to work on Friday.
Dr Albert Au of the Centre for Health Protection said the pair had not travelled out of Hong Kong recently.
He said they had recently visited a bar on Staunton Street and a restaurant in Sai Kung.
Au said officials were liaising with the US Consulate when it came to contact-tracing, adding that all the staff there would be required to get tested for Covid if the infections are confirmed.
In a statement, the consulate said the employees in question do not work in offices where there is interaction with the public, adding that the consulate building has been closed for deep disinfection and cleaning.
Meanwhile, the centre reported another 30 confirmed coronavirus infections on Monday, 16 of which were locally transmitted.
Thirteen infections are linked to a coronavirus outbreak at a gym in Sai Ying Pun, taking the total number of cases in this cluster to 122.
There were 14 new imported cases, including 10 foreign domestic helpers who recently arrived in Hong Kong.