A worker arranges boxes of imported frozen meat at a cold storage at Dalian port in Dalian, northeast China's Liaoning Province, April 8, 2020. (File photo: Xinhua)

TIANJIN, Dec. 21 (Xinhua) -- Tianjin Municipality in northern China has found the COVID-19 virus on a sample collected from the packaging of imported pig trotters, local authorities said Monday.

The city's COVID-19 prevention and control headquarters said that, during an inspection of imported cold-chain food, authorities detected the novel coronavirus in the samples taken from the packaging of pig trotters in a cold storage in Binhai New Area on Sunday. The food had been imported from Denmark.

Authorities have sealed the imported goods, which did not enter the market, and disinfected the environment. A total of 196 samples collected from the packaging of the frozen food and the environment tested negative for COVID-19 on Sunday.

Twenty-four people who had been in contact with the contaminated packaging are under quarantine. They have all tested negative for COVID-19 so far.

China has stepped up efforts to block the spread of COVID-19 through imported food. The Ministry of Transport released a guideline in mid-November to prevent the transmission of COVID-19 through cold-chain food imported via roads and waterways.

The State Council's joint prevention and control mechanism against COVID-19 has also unveiled a plan for full-chain, closed-loop, traceable management of imported cold-chain food.