A South Korean national working in southwest China's Chongqing Municipality tested positive for COVID-19 but was asymptomatic after returning to Seoul, according to Chongqing authorities.

The South Korean individual, an employee at the semiconductor company SK Hynix, boarded a flight from Chongqing to Incheon International Airport on Friday. On Saturday, SK Hynix in Chongqing reported to Chongqing officials that he tested positive for the virus but was symptom free after arriving in Seoul. 

Chongqing's health authorities have tested 3,283 people relevant to the new case, and 2,674 results of those tests returned negative. Some 493 samples from the environment also tested negative.

The city has launched an investigation into the source of the infection, officials said.