THE lethal H5N1 strain of bird flu has been detected at a poultry farm in Saudi Arabia and 50,000 birds have been culled, the agriculture ministry announced on Wednesday.

It said tests were carried out after 1,500 birds died in a farm of the Al-Kharj region, 150 kilometres south of Riyadh.

All the birds on the farm were subsequently culled and the area disinfected, with measures taken to ensure other farms in the area were not affected, the ministry said in a statement carried by the official SPA news agency.

It said no human case has been found and an investigation was taking place to determine the origin of the illness.

The kingdom banned all live poultry imports after bird flu was last detected in Saudi Arabia in March. In April, neighbouring Kuwait culled 1.7 million birds after the strain was found, but there no reports of human cases.

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