South Korean President Moon Jae-in said Sunday the government was waging "all-out responses" to contain the novel coronavirus as the country added 586 more cases, taking the total to 3,736.
South Korea has the largest national total in the world outside China, after it saw a rapid surge in the number of coronavirus cases in recent days.
Scores of events have been cancelled or postponed over the contagion, while the country's central bank has warned of a minus growth in the first quarter for the world's 12th-largest economy, noting the epidemic will hit both consumption and exports.
"The government is now waging all-out responses after raising the crisis alert to the highest level," Moon said at an Independence Movement Day ceremony, scaled down due to the outbreak.
"We will be able to overcome the COVID-19 outbreak and revive our shrunken economy," he added.
Samsung Electronics suspended operations at its domestic smartphone plant in Gumi -- 200 kilometres (210 miles) southeast of Seoul -- on Saturday for the second time in a week, after a third employee tested positive for the virus.
Auto giant Hyundai Motor also stopped operations at one of its Ulsan plants after an employee tested positive for the coronavirus.
Concerts by K-pop superstars BTS and the World Team Table Tennis Championships were among cancelled events, while sports leagues have modified their seasons to contain the virus.
K-pop star CHUNG HA was placed in self-quarantine when a member of her staff tested positive after visiting Italy last month, Yonhap news agency reported. The singer tested negative.
- 'Epicentre' -
Nearly 90 percent of the cases were in Daegu, the centre of the country's outbreak, and neighbouring North Gyeongsang province, the Korea Centers for Disease Control and Prevention said in a statement.
The country reported one more death Sunday, taking the total death toll to 18.
South Korea has an advanced health system and a free media, factors observers say improve the reliability of its statistics, with the numbers expected to rise as it checks more than 260,000 people associated with the Shincheonji Church of Jesus.
A 61-year-old female member developed a fever on February 10, but attended at least four church services in Daegu -- the country's fourth-largest city with a population of 2.5 million -- before being diagnosed.
Around 60 percent of the cases were linked to the entity, the KCDC said.
"Until now, the COVID-19 outbreak in the country has been excessively led by a specific group," said KCDC vice director Kwon Jun-wook.
Shincheonji apologised Sunday on behalf of its members who had kept their religion secret, adding: "It will be hard for our devotees to reveal their identity when political leaders... are recklessly criticising Shincheonji as the epicentre."
Daegu has filed a police complaint against the local branch of the sect for submitting an incomplete list of its members, while other provincial governments have warned of taking similar action.
The city's streets have been largely deserted for days, aside from long queues at the few shops with masks for sale, with authorities urging the public to exercise caution.
"The best way to prevent the COVID-19 is for the citizens to refrain from going outside," said Daegu mayor Kwon Young-jin.
But officials say they are not considering a citywide quarantine similar to Wuhan's lockdown, where the virus first emerged.
The new school term start has been delayed one week nationwide and three weeks in Daegu, while the US and South Korean militaries have postponed forthcoming joint exercises.