South Korea is facing a "grave" situation from the coronavirus outbreak, Prime Minister Chung Sye-kyun said Saturday as the country reported 229 new cases in the sharpest spike in infections yet.
Many of new cases involved patients being treated in hospital for mental health issues but also included a Samsung employee and eight people who had just returned from a trip to Israel.
The national toll of 433 is the highest outside China apart from the Diamond Princess cruise ship in Japan, with the jump in cases at the hospital in the southern city of Cheongdo following a similar spike among members of a religious sect in the nearby city of Daegu.
"The government believes the situation of the COVID-19 infections is turning into a grave phase, and is making every effort to prevent the spread," the prime minister said in a national address late Saturday.
He called on Koreans to refrain from attending large gatherings including religious services to help curb the spread of the virus. Chung also warned that the government would act firmly against people hoarding face masks or taking part in now-banned mass rallies.
Among the new cases was a Samsung Electronics employee at a plant in Gumi, 200 kilometres (210 miles) southeast of Seoul and close to Daegu, leading the tech giant to say it would suspend operations there until Monday.
Meanwhile, 95 of the newly confirmed cases were "related" to patients or staff at Cheongdo Daenam Hospital in Cheongdo, the Korea Centers for Disease Control and Prevention (KCDC) said.
"Most of the hospital's patients who have been diagnosed are those who had been staying as inpatients for mental illnesses," vice health minister Kim Gang-lip told reporters.
Some cases show "no confirmed epidemiological connections", meaning they are not sure where or how they contracted the virus, he added.
Authorities reported another death on Saturday, taking the toll to two. Both victims had been inpatients at the hospital.
- Church cluster -
Separately, more than 200 members of the Shincheonji Church of Jesus have now been infected, starting with a 61-year-old woman who attended at least four services at the church's Daegu branch before being diagnosed.
KCDC said some 9,300 Shincheonji members in Daegu have either been quarantined at facilities or been asked to stay at home. Among them, 1,261 said they had symptoms, health officials added.
The mayor of Daegu -- South Korea's fourth-biggest city, with a population of more than 2.5 million -- has advised locals to stay indoors, while access to a major US military base in the area has been restricted.
One of the Shincheonji members in Daegu visited China -- where the deadly virus was first detected -- in January, while three others are believed to have travelled to other countries, KCDC director Jung said.
Cheongdo, 27 kilometres south of Daegu, is the birthplace of Shincheonji's founder Lee Man-hee.
County officials said on Friday that a three-day funeral was held for one of the church members three weeks ago at a hall near the Cheongdo hospital, where more than 110 cases have now been confirmed.
Shincheonji is often accused of being a cult and claims its founder Lee has donned the mantle of Jesus Christ and will take 144,000 people with him to heaven on the day of judgement.
But with more church members than available places in heaven, they are said to have to compete for slots and pursue converts persistently and secretively.
President Moon Jae-in on Friday called for a "thorough investigation" of everyone who attended the funeral and Shincheonji services.
Shincheonji offered an apology, suspending its services and gatherings nationwide.
"We are deeply sorry that because of one of our members, who thought of her condition as a cold because she had not travelled abroad, led to many in our church being infected and thereby caused concern to the local community," it said in a statement.
But its leader Lee told his followers the outbreak had been "caused by the Devil" and compared it to the biblical testing of Job, Yonhap news agency reported.
Among the new cases in South korea, 92 were 'related' to patients or staff at a hospital