The Agriculture and Forestry Ministry announced Saturday that South Korea has not had any reports of new suspected cases of a deadly avian influenza since last Sunday, indicating that the spread of the virus appears to be in check.

Still, the ministry is remaining cautious about a possible recurrence of the disease as it tries to confirm whether a duck farm in the city of Cheonan has been hit by the bird flu.

Ducks at the farm earlier showed signs of the disease, prompting the authorities to launch a thorough investigation.

The ministry is expected to release the outcome of its inspections in two or three days, and plans to maintain quarantine measures for at least 30 days at each place where the disease is confirmed to have broken out.

Since the flu surfaced on Dec. 15, chickens and ducks at 14 farms in North Chungcheong Province, the epicenter of the outbreak, tested positive for the avian virus, a variant of which killed several people in Hong Kong last year.

There were, however, no indications that the disease has crossed the species barrier to humans in South Korea. Health officials said that none of the more than 1,500 people who have been exposed to the flu have exhibited any signs of infection.