The Korea Centers for Disease Control and Prevention says the country added 46 new cases of coronavirus.
While most of the cases were imported, the figure includes a cluster linked to a Russian-flagged ship at the port in Busan.
Reports said some 16 members of the 21-man crew in Russian-flagged ship have been tested positive to the coronavirus.
The captain, who left the ship before it set sail from Vladivostok, also tested positive for COVID-19 in Russia.
Meanwhile, South Korea has put 160 port workers who came into contact with the crew in Busan into isolation.
Also, Cluster infections in Seoul and outside the capital has continued to grow.
City authorities are considering the need to tighten movement restrictions again in order to control the spread of the disease. Reports said.