South Africa said on Friday a bird flu outbreak on ostrich farms is different from the strain that killed 24 people in Asia, but it halted all poultry exports as a precaution. The Department of Agriculture said tests had identified the outbreak as the H5N2 strain -- highly dangerous for birds, but not the H5N1 strain that can kill people and decimated Asian poultry stocks earlier this year. "The Department of Agriculture has voluntarily stopped exports of poultry and poultry products from South Africa until the outbreak has been dealt with successfully," the department said in a statement. Officials said around 1,500 ostriches had already died from the disease, and they would slaughter thousands of birds on around 15 farms quarantined on Thursday over a 30 km (19 mile) radius from two infected farms near Middleton, Eastern Cape. Reuters reporters at one of the affected farms saw a trailer loaded with dead ostriches. "We have been advised that a vaccine is not recommended as the strain of the virus mutates so quickly that the best option is to cull. We expect to cull about 6,000 ostriches," said Njabulo Nduli, the Department of Agriculture's deputy director general for agricultural production and resources management. Armed forces personnel have helped agriculture department officials mount road blocks to enforce the quarantine area in Eastern Cape province since Thursday to try to protect the country's $190 million-a-year ostrich export industry. --More 1614 Local Time 1314 GMT