The Agriculture, Fisheries and Conservation Department said it was one of 77 hamsters handed over by their owners, after 11 hamsters from a pet shop in Causeway Bay were found to have been infected with the Delta variant.
The government had asked people to hand in hamsters they bought on or after December 22, saying the animals will be tested before being put down.
The department said 2,512 small mammals had been culled as of Saturday.
The department said further tests found seven more hamsters from the pet shop were carrying the virus, as well as three from another outlet run by the same company and its warehouse in Tai Po.
Environmental samples from these places, as well as from other branches located in different parts of the city also tested positive for the virus.
In a statement, the department renewed its “strong advice” for people to hand in their recently-bought hamsters.