Saudi authorities have culled nearly 160,000 birds after a new case of the deadly strain of bird flu was found on a farm outside Riyadh, state media said on Tuesday.

The Saudi Press Agency said 158,000 birds were exterminated at al-Kharj, 150 km (94 miles) south of the capital, after the H5N1 strain of bird flu was found there.

Authorities killed thousands of birds in al-Kharj and other sites near Riyadh in November, as inspection teams combed farms and markets around the city of about 4 million people.

In March, Saudi Arabia said the deadly H5N1 strain of bird flu had been discovered in peacocks, turkeys, ostriches and parrots at a house in the east of the kingdom and that an unspecified number of birds in the area had been culled.

The Saudi government says it has large stocks of Tamiflu anti-flu tablets in case the virus spreads to humans.

The virus has caused more than 200 deaths in humans globally since 2003, according to World Health Organisation data.

Although most people who have caught bird flu have had direct or indirect contact with infected fowl, experts fear the constantly mutating virus could change into a form easily transmitted from person-to-person. - Reuters