Saudi state media say authorities have destroyed nearly 160,000 birds following the discovery of bird flu south of the capital, Riyadh.

The Saudi Press Agency reports Tuesday that the birds tested positive for the H5N1 strain of bird flu, which can be deadly to humans. The outbreak was discovered on a farm in the al-Kharj region, about 80 kilometers south of the capital.

Authorities destroyed thousands of birds in the region last November to contain another outbreak of the virus.

Various forms of bird flu are common in birds and rarely affect humans. The World Health Organization says the H5N1 strain of the virus has killed at least 223 people worldwide since 2003.

Saudi Arabia has not reported any human cases of the disease.

Victims generally contract the disease from sick or dead birds, but health authorities are concerned the virus could change into a form easily passed between humans.

Some information for this report was provided by AFP and Reuters.