RIYADH (AFP) - Saudia Arabia´s agriculture ministry confirmed Friday that the entire stock of three poultry farms outside the capital had been culled due to an outbreak of bird flu, the official SPA news agency said.

The ministry said in a statement that all birds in the three farms west and south of Riyadh were culled, but gave no figures.

"It is almost certain that migrant birds are the source of the disease," the ministry said.

On Wednesday, the ministry had announced that 50,000 birds were culled at a poultry farm in Al-Kharj, 80 kilometres (50 miles) south of Riyadh, after the deadly H5N1 strain of bird flu was detected there.

But the virus was later detected at two other farms, about 80 kilometres west of the capital.

Agriculture Minister Fahd Balghnaim was quoted as saying earlier Friday that around 90,000 chickens had been lost at the two western farms.

Saudi Arabia banned all live poulty imports after bird flu was last detected in the kingdom in March. In April, neighbouring Kuwait culled 1.7 million birds after the strain was found.

There are no reports of the disease spreading to humans in either country.

The H5N1 strain first emerged in Asia in 2003, and has caused some 205 deaths in humans, with Indonesia and Vietnam among the worst hit countries, according to World Health Organisation figures.