The World Health Organization (WHO) on Thursday urged people not to fear catching the novel coronavirus from food, after Chinese testers found traces on food and food packaging.

The virus was found Tuesday in the Chinese city of Shenzhen during a routine check on samples of frozen chicken wings imported from Brazil, city authorities said.

The authorities said they immediately screened people who had been in contact with the contaminated products, plus their relatives, and all the tests came back negative.

In China's eastern Anhui province, the mayor of Wuhu announced Thursday that the virus had been discovered on the packaging of shrimp imported from Ecuador, which had been kept in a restaurant freezer.

The WHO said there was no need to panic -- and there were no examples of the respiratory disease being transmitted through food.

"People are already scared enough and fearful enough in the COVID pandemic," WHO emergencies director Michael Ryan told a virtual press conference in Geneva.

"People should not fear food or food packaging or the processing or delivery of food.

"There is no evidence that food or the food chain is participating in the transmission of this virus.

"Our food, from a COVID perspective, is safe."

Maria Van Kerkhove, the WHO's COVID-19 technical lead, said the United Nations health agency was aware of the reports and understood that China was looking for the virus on food packaging.

"They've tested a few hundred thousand samples of looking at packaging and have found very, very few, less than 10 positive in doing that," she said.

"We know that the virus can remain on surfaces for some time.

"If the virus is actually in food -- and we have no examples of where this virus has been transmitted as a food-borne, whereas someone has consumed a food product -- the viruses can be killed, like other viruses as well, if the meat is cooked."