The ministry said it would take about one to three weeks toconfirm if the soldier, said to be 22-years old by local media,had been infected with the H5N1 strain of bird flu.
"The soldier's symptoms are consistent with that ofsuspected AI (avian influenza) patients, according to WorldHealth Organisation standards, but the clinical symptoms alsoresemble bacterial pneumonia so we are on a close watch," theministry said in a statement.
The soldier, who is being treated in a quarantine ward, hada high fever and respiratory problems. He has shown signs ofimprovement after being treated with antibiotics, it said.
On Monday, South Korea's farm ministry said it planned tocull a record 5.3 million birds as it announced its 17th caseof bird flu in three weeks, in what has become the country'sfastest and biggest outbreak of avian influenza.
No human deaths from the disease have been reported so farfrom the country.
Some 240 human deaths have been reported globally from theH5N1 strain and 381 confirmed cases of infection since 2003,according to World Health Organisation data.
(Reporting by Jon Herskovitz and Lee Jiyeon; Editing byKeiron Henderson)