Chinese customs have tested 1.49 million samples of cold-chain imports for the novel coronavirus, and 79 of them had returned positive as of Thursday, the General Administration of Customs said in a statement on Friday.

The administration said that 56 foreign manufacturers involved in shipping contaminated food products to China have been suspended from filing import applications for one to four weeks, as a preventive measure to fend off the virus' spread through cold-chain imports.

As the global COVID-19 pandemic situation remains severe, the administration said it has stepped up testing and disinfection over cold-chain imports and tightened inspection over the source of cold imports.

"We have suspended imports of 129 suppliers from 21 countries where employees had been infected with the virus. Among them, 110 companies voluntarily halted exports to China," it said.

The administration has also examined about 200 food manufacturers overseas and disinfected packages of nearly 19 million pieces of cold imports at ports.

Traces of the virus were first detected on the outer packaging of frozen seafood and meat products from overseas since the second quarter of last year. In late January, imported cherries and milk powder also tested positive for the virus.

Data from the administration show that the latest positive rate of the national sampling and testing of imported food stands at about 0.53 per 10,000, higher than the rate of 0.36 per 10,000 reported in mid-January.

Liu Zhaoping, a researcher at the China National Center for Food Safety Risk Assessment, said research has indicated that the virus can survive on cold-chain food products and their packaging during long-haul shipping, which is likely to cause human infection.

Dockworkers who are constantly exposed to contaminated goods are at the highest risk, he added.

But the risk of consumers contracting the virus from eating or touching imported food is relatively minimal, experts have said.

Feng Zijian, deputy director-general of the Chinese Center for Disease Control and Prevention, said during a previous interview that positive test results are not synonymous with being infectious.

"No infections have been found in consumers due to exposure to contaminated imported food," he said.

An international expert team convened by the World Health Organization to study the origin of the pandemic in China earlier this year did not rule out the possibility that the novel coronavirus was introduced into human population through cold-chain food products. But they also added that the most likely pathway is that the virus had jumped from an animal host to human through intermediary species.