In a Reuters report, it has been stated that China's Shenzhen Stock Exchange is seeking further information from shopping mall operator Guangdong Highsun Group Co after Highsun announced it was backing the development of an African swine fever vaccine.

Highsun said on Tuesday (11 June) that it would spend 900 million yuan ($130.09 million), or 26 percent of its 2018 net assets, on supporting research into a natural compound the company claimed had been shown to prevent African swine fever, a disease deadly to pigs that is ravaging herds across Asia.

Researchers around the world have tried for years to develop a vaccine for the disease but have not yet been successful.

Highsun's announcement triggered a 10 percent surge in its shares, causing a trading suspension.

The exchange said it was seeking clarity on several issues, including additional data regarding the vaccine's success in preventing African swine fever and whether the researchers had government approval to conduct research on the virus.

Research on and the handling of the African swine fever virus is strictly regulated by Beijing.

The exchange also wanted confirmation that the compound, a polysaccharide injection, had been patented as claimed. A polysaccharide is a carbohydrate made up of a chain of sugar molecules.

An official from Highsun, who asked not to be identified, said the company was preparing a response to the Shenzhen Exchange's questions and declined to comment further.

African swine fever kills almost all the pigs it infects. The breeding herd in China, the world's top pork producer, has declined by 24 percent, the agriculture ministry said on Thursday, a record drop, owing to the disease.

Highsun said that preliminary research had found the polysaccharide to be 92 percent effective in preventing the disease in clinical trials.

The Bureau of Agriculture and Rural Affairs for Hainan province said on its website on Thursday (13 June) that it had supported a research team that had isolated a polysaccharide compound from tropical plants, which had shown a "certain preventive effect" against African swine fever.

However, more research was needed on areas including the possible impact of virus mutation on prevention and the safety, stability and feasibility of industrial production of the compound.

It is not clear if the bureau is referring to the same team backed by Highsun.

The Hainan Agriculture Bureau did not answer calls for a comment on the statement.

Highsun's shares rose 7.3 percent to 3.38 yuan ($0.49) a share after resuming trading on Thursday.

($1 = 6.9185 Chinese yuan renminbi)