South Korea has reported 52 new confirmed cases of the coronavirus on Friday, taking the national total to 156 with the majority in Daegu, the country's fourth-largest city with a population of 2.5 million.
Of the national tally, 111 patients are from Daegu or nearby. Most have been traced to an infected 61-year-old woman known as "Patient 31" who attended services at a branch of the Shincheonji Church in recent weeks.
As of Friday more than 400 members of the church are showing symptoms of the disease, though tests were still ongoing, Daegu Mayor Kwon Young-jin said at a briefing.
Officials in Seoul said they were closing Shincheonji churches there.
South Korean President Moon Jae-in has called for officials to closely investigate the church services, as well as a funeral service at a hospital in nearby Cheongdo County that was attended by many church members and is now the site of another cluster of cases.
That hospital was also home to the first coronavirus patient to die in South Korea, though officials are still seeking to confirm his exact cause of death.
Lee Man-hee, the leader of a South Korean religious movement at the centre of the country's largest coronavirus outbreak, called the disease the "devil's deed" and a test of faith.
He called on his followers to obey instructions from government authorities and to avoid holding meetings.
Health authorities have described the outbreak in Daegu and the surrounding areas as a "super-spreading event".
South Korean officials on Friday designated two areas as "special care zones" while troops were confined to their bases in an effort to contain the spread of the virus.
The government also plans to send military medical staff, and provide temporary isolation facilities.
Malls, restaurants and streets in Daegu were largely empty with Kwon, the mayor, calling the outbreak an "unprecedented crisis".
He said the city would ban any kind of mass gathering and repeated a request for residents to stay at home.
Many of South Korea's initial patients have recovered, but the sudden and rapid spread in recent days has created alarm because there are a still many important unknowns surrounding the virus. It can cause pneumonia, which has been deadly in some cases.
In Seoul, city officials said they would not allow any of the large protests and demonstrations that are often held on the weekends, Yonhap reported.
Australian Associated Press