South Korea reported 161 more coronavirus cases Monday, taking the nationwide total to 763 and making it the world's largest total outside China.
The country has seen a rapid surge in the number of coronavirus cases since a cluster of infections emerged from a religious sect in the southern city of Daegu last week.
Most of the country's cases are connected to the Shincheonji Church of Jesus in the southern city of Daegu, including 129 of Monday's confirmations, the Korea Centers for Disease Control and Prevention said in a statement.
Two more people had died, it added - both of them connected to a second cluster around a hospital in Cheongdo - taking the toll to seven.
"The COVID-19 incident faces a grave turning point. The next few days will be crucial," President Moon Jae-in said following a government meeting on the virus.
"The government will raise the alert level to the highest level of 'grave' according to experts' recommendations and drastically strengthen our response system," Mr Moon said.
He also urged officials to take "unprecedented powerful measures" to contain the outbreak.
The government ordered all schools and kindergartens nationwide to extend the spring break by a week in an effort to prevent further spread of the virus.
South Korean President Moon Jae-in, center, speaks during a meeting at a government complex in downtown Seoul, South Korea, Sunday, Feb. 23, 2020. Source: AAP
While more measures have not been introduced, South Korean media reports say the highest "red" alert level would allow the government to restrict public transport, ban group events such as religious activities and protests, and enforce tighter entry restrictions on the country.
The outbreak has forced South Korean tech giant Samsung Electronics to suspend operations at its smartphone plant in Gumi, 200 kilometres southeast of Seoul, after one of its employees was infected on the weekend.
The Gumi plant manufactures high-end products for the domestic market, including Samsung's latest Galaxy S20 and luxury Galaxy Z Flip models.
On Sunday South Korea reported 169 new cases and three deaths, taking the countrywide toll to five.
Later, Yonhap news agency said a sixth patient had died.
One of the victims was a patient being treated for mental health issues at a hospital in Cheongdo, a southern city linked to the religious sect where around 100 new cases were reported.
Among the latest confirmed cases, 95 were linked to the Shincheonji Church of Jesus in the nearby city of Daegu, according to the Korea Centers for Disease Control and Prevention.
More than 300 cases have been linked to the church, starting with a 61-year-old woman who developed a fever on 10 February and attended at least four services in Daegu before being diagnosed.
Some 9,300 Shincheonji members in Daegu have either been quarantined or have been asked to stay at home, KCDC director Jung Eun-kyeong said, with more than 1,240 saying they had symptoms.
'National crisis'
Daegu - South Korea's fourth-biggest city with a population of 2.5 million - reported more than 90 new cases on Sunday, bringing the city's total to 247, mayor Kwon Young-jin said.
The mayor asked all Shincheonji members with symptoms to come forward and be tested, with hundreds of members yet to be reached by authorities.
Mr Moon described the situation in Daegu and Cheongdo - the birthplace of Shincheonji's founder Lee Man-hee - as a "national crisis", adding the cities will receive "full support" for any lacking medical supplies and personnel.
Shincheonji, often accused of being a cult, claims its founder has donned the mantle of Jesus Christ and will take 144,000 people with him to heaven on judgement day.
But with more church members than available places in heaven, they are said to have to compete for slots and pursue converts.
In a video statement read out by its spokesman, Shincheonji apologised for "causing concern", but insisted it was cooperating with health authorities for the "early cessation" of the situation.
Israel pilgrimage
The spokesman refuted public criticism blaming his church over the spike in the number of infections, noting the virus had broken out in China.
"Please be aware that the Shincheonji Church of Jesus and its members are the biggest victims of the COVID-19," he said.
Among the new cases were 18 people recently returned from a group pilgrimage to Israel, the KCDC said.
It was unclear how they had been infected, but authorities said one of the victims was likely exposed to the virus before their trip, given Israel has reported only one confirmed COVID-19 case so far.
Tourists from Korea wearing protective mask from Coronavirus walk with their belongings at the Ben Gurion airport near Tel Aviv, Israel, Sunday, 23 February. Source: AAP
Israel has issued an entry ban on South Koreans and refused to allow non-Israelis to disembark from a Korean Air plane on Saturday.
The US State Department on Saturday raised its travel advisory for South Korea, joining a handful of countries bolstering their vigilance after its rapid spike in the number of infections.
Britain has also advised its nationals "against all but essential travel to Daegu and Cheongdo".
