The agriculture authorities in Gansu province have confirmed that tests on pork products sold in the region returned positive results for African swine fever. Further tests are underway.

The official response was prompted by a leaked report, circulated online last week, that said 83 out of 149 samples of processed pork products for sale in Gansu had tested positive for nucleic acid associated with African swine fever.

The samples were collected in five cities in the province, mainly from grocery stores, farmers' markets and wholesale suppliers. A variety of meat products were involved, including sausages, frozen dumplings, meatballs and bacon, the report said.

The 11 manufacturers of the problematic products are located in Shandong and Henan provinces, and in Shanghai. The report did not say when the tests were conducted.

The revelation has fueled concerns from consumers as household brand names－including Sanquan and Synear, known nationwide for their popular frozen dumplings－were listed as tainted in the report.

An official with the disease control and prevention branch of the Gansu Department of Agriculture and Rural Affairs told Beijing News over the weekend that the leaked results emerged from a preliminary stage of the investigation and that the provincial authorities were doing more inspections.

Two African swine fever outbreaks were uncovered in Gansu last month. The findings of an investigation into the possible routes of infection said it was possible that pork products carried from outside the province had played a role in spreading the disease, the newspaper quoted the official as saying.

The official, who was not named, added that final test results for the samples had not been released, and no enterprises had received notices from the authorities.

Zhu Zengyong, an analyst at the Chinese Academy of Agricultural Sciences, said preliminary tests for African swine fever usually use a reactive paper because of its convenience and speed. In order to verify the strain of virus, the samples need to be sent to a laboratory for further analysis.

"In most cases, processed meat products are found to be positive for the contagious virus because some meat from affected pigs may constitute some of the raw material in the process," he said.

Since the country's first outbreak of African swine fever was detected in Liaoning province in August, the Ministry of Agricultural and Rural Affairs has reassured the public that the disease, while deadly for pigs, is not harmful to humans.

Nevertheless, the apparent contamination of pork products that arrived in markets to be sold sparked heated discussions online.

On Thursday, a netizen referred to media reports that three samples of Sanquan dumplings, produced in Henan province and sold in Hunan province, had tested positive for African swine fever, and asked the company if the news was true.

The company's reply, posted on the interactive platform of the Shenzhen Stock Exchange on Friday morning, said it had not received any official notice and would look into the matter.

As of Jan 14, China had reported African swine fever outbreaks in 24 provinces, autonomous regions and municipalities, leading to the culling of around 916,000 pigs. The ministry said the spread of the disease slowed in January but the outlook for controlling it remained complex.