BEIJING/SHANGHAI/BRASILIA (Reuters) - Two cities in China have found traces of the new coronavirus in cargoes of imported frozen food, local authorities said on Thursday, although the World Health Organization downplayed the risk of the virus entering the food chain.

A sample taken from the surface of frozen chicken wings imported into the southern city of Shenzhen from Brazil, as well as samples of outer packaging of frozen Ecuadorian shrimp sold in the northwestern city of Xian, have tested positive for the virus, local Chinese authorities said.

Seven Argentine meat processing plants are temporarily not exporting to China because they have registered cases of COVID-19 among their employees, a source from the Argentine agricultural health agency Senasa said on Thursday.

The first cluster of COVID-19 cases was linked to the Huanan seafood market in the Chinese city of Wuhan.

Authorities said the virus was found in the market on a chopping board on which imported salmons were handled.

How the virus entered Xinfadi market in the first place is yet to be determined, the Chinese Center for Disease Control and Prevention said in its latest update of the investigation in July.