The government will ramp up efforts to monitor local poultry farms and the distribution network of ducks and chickens to prevent the further spread of avian influenza, officials said Wednesday.

A total of seven AI outbreaks have been reported nationwide since Sept. 18, when ducks at two poultry farms, about 400 kilometers south of Seoul, tested positive for a virulent strain of bird flu.

The farm ministry said a day after the Chuseok holiday that nationwide decontamination is under way with inspectors already checking regions that are most vulnerable to AI outbreaks.

"A special quarantine and inspection period will run from Thursday through May 31 of next year," Deputy Agriculture Minister Lee Joon-won said. "The period is timed to coincide with the end of the Chuseok holiday and the arrival of migratory birds from the north."

Chuseok, or Korean Thanksgiving, which fell on Sunday this year, is a particularly difficult time for quarantine officials because there is a large movement of people across the country.

October marks the start of the migratory season for wild birds that have been known to spread AI to domestic poultry farms.   

Lee said that detailed tests on the strains showed that all outbreaks confirmed in the past few weeks were similar to those that hit the country from Sept. 24, 2014, through June 10 this year.

"The latest outbreaks are not from a new outside source, but came from a virus that had stayed dormant for the past few months," the official said.

Close inspections of the affected areas show that local poultry middlemen may have inadvertently spread the virus, he said.

Authorities are in the process of checking some 270 facilities and bird farms these middlemen visited to check for AI, the official added. Seoul has ordered all poultry agents to register with authorities following past outbreaks.

"It is likely that new bird flu cases will be reported in the future," Lee warned.

Since 2003, South Korea has reported five outbreaks that have cost the country about 620 billion won ($518 million).

Besides bird flu, the farm ministry said it will beef up inspections and vaccinations of cloven-hoofed animals like pigs and cows to prevent another outbreak of foot-and-mouth disease.

Since the last outbreak on April 28, there have been no new cases in the country, but the government said it is not taking any chances, especially since there have been numerous outbreaks reported in neighboring countries such as China. (Yonhap)