South Korean authorities have started culling thousands of chickens following a bird flu outbreak, the country’s farm ministry said.

Late on Thursday, the ministry said the strain of bird flu at the farm in Gimje, about 215 km south of Seoul, was confirmed as the deadly H5N1 strain, Reuters reports.

Therefore, all 308,000 chickens and their eggs at 7 farms near the outbreak site will be killed. The owner at the farm in Gimje reported the outbreak early this week after about 3,000 chickens at the farm start dying late last month.

The ministry said the National Veterinary Research and Quarantine Service will conduct an investigation into why the outbreak occurred. Also, the Korea Center for Disease Control and Prevention will be placed on standby in case of human infection. No South Korean has contracted the disease so far.

The ministry has also imposed restrictions on the movement of poultry within a 10 km (6 mile) radius.

Poultry farms across South Korea were hit by seven outbreaks of the deadly virus between November 2006 and March 2007, resulting in the slaughter of nearly 2.8 million birds.

According to the World Health Organization, at least 238 people worldwide have died from bird flu since 2003. Indonesia has alone 107 deaths from the bird flu.

Health experts fear that the virus, which is usually spread through human-bird contact, could mutate into a form easily passed from human to human and millions of people could die because they would have no immunity to the new strain. So far, most human cases have been linked to contact with infected birds.