China has discovered a strain of bird flu that is deadly to humans at a farm in the far western region of Xinjiang, the latest outbreak of the disease scientists warn could cause a future global pandemic.

More than 13,000 geese were slaughtered to curb its spread, the Agriculture Ministry said on Thursday, after hundreds of dead geese were found on the farm in Xinjiang’s Tacheng district and some 1,000 showed signs of illness.

“The Xinjiang Veterinary Office, in accordance with animal epidemic prevention regulations, has adopted measures to seal off and sterilise the area,” the ministry said in a statement. “Presently, the outbreak has been brought under control.”

Tests showed the cases were caused by the H5N1 virus, which first surfaced in poultry in Hong Kong and China eight years ago and has killed more than 50 people in Southeast Asia since it swept across large parts of the region in 2003.

Scientists have warned that Avian flu, which is infectious in birds but does not spread easily among humans, could mutate into a form better able to pass from animals to people, possibly triggering a global pandemic.

They say such a pandemic would likely start in Asia and could kill millions and result in devastating economic losses.

China last month reported an outbreak in wild birds in the northwestern province of Qinghai, prompting a vaccination campaign that extended to neighboring regions, including Xinjiang.

But experts said the latest cases were unrelated and that migratory birds in Qinghai were unlikely to have been the cause.

“It’s a completely separate outbreak. Birds won’t be flying north at this time of year anyway. So there is absolutely no link between the two,” said Lew Young, a researcher at the Mai Po Nature Reserve in Hong Kong.

A spokesman at the World Health Organization would not speculate on the potential threat to humans from the Xinjiang outbreak.

“After all, it’s not the first time it has been found in domestic poultry, and China is no stranger to this sort of situation,” Roy Wadia said.

Last year, China controlled outbreaks of bird flu with a combination of vaccinations, culling and surveillance.

“The processes that have to be done are all in place and they know how to contain outbreaks pretty quickly. We always stress that the utmost precaution be taken,” Wadia said.

An official surnamed He at the Epidemic Control Office in Tacheng, which is in China’s far northwest near the Kazakh border, said there had been no human cases.

Hong Kong has also said it would step up surveillance of local farms and retail markets for any irregularities among the poultry population.

The city, which gets much of its food from China, has not imported any live birds or poultry meat from Xinjiang, but as a precaution mainland authorities have suspended any such sales to the territory.