Beijing, Dec 6 (IANS): At least 43 people have been placed under quarantine after a frozen-food sample in China's Heilongjiang province tested positive for the novel coronavirus, local authorities said.

On Saturday, the authorities in the provincial capital of Harbin launched an emergency response after a third-party inspection agency found the frozen-food sample from a local trading company that tested positive for the virus the previous day, Xinhua news agency reported.

As of 5 p.m. Saturday, 43 close contacts had been quarantined in designated places and 109 were under observation at home, according to the Harbin epidemic response headquarters.

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.

They are also tracking the infection source of the virus.

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

Saturday's developments come only a week after authorities in Wuhan, where the novel coronavirus is likely to have originated in December 2019, said that three imported frozen food packaging samples had tested positive for Covid-19.

The municipal health commission said on on November 28 that two samples were taken from frozen beef from Brazil in a refrigerated warehouse and the other one from frozen basa fish from Vietnam in another warehouse.

China has increased efforts to block Covid-19 transmission through imported foods.

The Ministry of Transport had released a guideline earlier this month to prevent the transmission of the virus through imported cold-chain foods in road and water transportation.

The State Council joint prevention and control mechanism against Covid-19 has also unveiled a plan to realize full-chain, closed-loop, traceable management of imported cold-chain foods.