Disease control and prevention workers collect samples from frozen products in Tianjin's Nankai district on Nov 9, 2020. [Photo/China Daily]

A total of 43 people have been placed under quarantine after a frozen-food sample in Northeast China's Heilongjiang province tested positive for novel coronavirus, local authorities said Saturday.

Authorities in Harbin, capital of Heilongjiang Province, have launched an emergency response after a third-party inspection agency found a frozen-food sample from a local trading company that tested positive for the coronavirus on Friday, according to the Harbin epidemic response headquarters.

As of 5 pm Saturday, 43 close contacts had been quarantined in designated places and 109 were under observation at home.

A total of 1,350 samples from these people, food products and the surrounding environment have been taken. The 989 samples tested so far all showed negative results.

Authorities have disinfected and sealed off the processing and storage facilities of the frozen-food products and sealed up the related frozen-food production materials and semi-finished products.

Authorities are tracking the infection source of the virus.

Also on Saturday, authorities in Yaodu district in the city of Linfen, North China's Shanxi province, announced that the outer packaging of imported fish product from a local farm-produce market tested positive for the virus.