South Korea's coronavirus cases nearly doubled Friday, rising above 200 and making it the worst-affected country outside China as the number of infections linked to a religious sect spiked.

A total of 100 new cases were confirmed by the Korea Centers for Disease Control and Prevention (KCDC), 85 of them connected to the Shincheonji Church of Jesus in the southern city of Daegu.

The mayor of Daegu -- South Korea's fourth-biggest city, with a population of over 2.5 million -- has advised locals to stay indoors, while access to a major US military base in the area has been restricted.

People were out and about on the streets Friday, with most wearing masks, but many businesses were closed due to the outbreak.

Workers on motorcycles sprayed disinfectant outside the Shincheonji church in the city, where passer-by Seo Dong-min, 24, told AFP: "With so many confirmed cases here I'm worried that Daegu will become the second Wuhan," referring to the Chinese city where the virus first emerged.

Thirty-nine of South Korea's new coronavirus cases have been linked to the Shincheonji Church of Jesus Thirty-nine of South Korea's new coronavirus cases have been linked to the Shincheonji Church of Jesus Photo: AFPTV / Yelim LEE

Shincheonji is often accused of being a cult and claims its founder, Lee Man-hee, 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.

The KCDC said one more virus case had been confirmed at a hospital in Cheongdo county near Daegu where a total of 16 infections have now been identified, including a long-stay patient who died Wednesday after showing symptoms of pneumonia.

Workers spray disinfectant outside the Shincheonji church in the South Korean city of Daegu after members fell ill with the novel coronavirus Workers spray disinfectant outside the Shincheonji church in the South Korean city of Daegu after members fell ill with the novel coronavirus Photo: AFP / Jung Yeon-je

Cheongdo is the birthplace of Shincheonji's founder Lee, and county officials said a three-day funeral was held for his brother three weeks ago at a hall owned by the hospital.

President Moon Jae-in called for a "thorough investigation" of everyone who attended the funeral and Shincheonji services.

"If you simply rely on the information provided by the church, the process can be slow," he told a cabinet meeting. "We need faster measures."

The streets of Daegu in South Korea remained active on Friday despite a coronavirus outbreak The streets of Daegu in South Korea remained active on Friday despite a coronavirus outbreak Photo: AFP / Jung Yeon-je

KCDC said 4,475 Shincheonji members had been tested in Daegu and 544 said they had symptoms.

The city's renowned Mijin restaurant, which has been in business for over 40 years, was closed, with a notice reading: "For your safety, we are suspending the business until coronavirus-19 is under control. We wish you and your family good health."

And Lee Yoo-jin, 73, who runs a dress shop in the city centre, told AFP: "I have not had a single customer this week. I have run the shop for over 20 years and never have I seen such a drop."

Residents expressed frustration, with a passer-by at the church saying authorities should have closed a nearby subway station for cleaning.

"Now it's all over the place," said the woman, surnamed Kim. "It's too late now."

The central government on Friday declared Daegu and Cheongdo "special management zones", with Prime Minister Chung Sye-kyun saying the region would be supported with medical personnel, beds and equipment and the cabinet will meet three times a week to discuss the outbreak.

Authorities in Seoul banned public rallies at three main locations on health and safety grounds.

The US army garrison in Daegu -- where around 10,000 soldiers, civilians and family members live or work -- has restricted access and instructed any American troops who recently attended Shincheonji services to self-quarantine.

"Please avoid public places and public transportation, to include stores, restaurants, subways and other heavily congested areas."

Shincheonji has closed all its facilities 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.