The number of infections rose to 64 after 14 new cases, including one death, of Middle East Respiratory Syndrome (MERS) were confirmed last night, the health ministry said.
It is the largest outbreak outside Saudi Arabia where it has infected more than 950 since 2012.
As of today, more than 2,300 people had been placed under quarantine of varying degrees. About 2,100 were told to stay home and strictly limit their interactions with others, while about 200 were isolated in state hospitals.
However, Busan city authorities reported an additional case in the country's southern port and second-largest city, sparking alarm that the outbreak may spread nationwide.
More From This Section
The case was not included among the 14 new infections confirmed by the health ministry.
Acting Prime Minister Choi Kyung-Hwan vowed today that "all-out efforts" would be made to curb the spread of the disease in Asia's fourth-largest economy.
He urged the public not to panic, saying all 64 patients had already been in hospital quarantine.
"People should not overreact and should cooperate closely (with the government) to minimise negative impact on the economy," he said.
The government will step up monitoring on those placed under observation, including tracking the locations of those in quarantine at home via their mobile phones, Choi said.
"Please understand that it is an inevitable measure to ensure the safety of your neighbours and families," Choi said.
The first case -- reported on May 20 -- was of a 68-year-old man diagnosed in the city of Pyeongtaek, about 65 kilometers south of Seoul, after a trip to Saudi Arabia.