SEOUL (Reuters) - South Korea reported 231 new cases of a coronavirus, taking total infections to 833, health authorities said on Monday, a day after raising its infectious disease alert to the highest level.

Many new cases have been linked to a church in the southeastern city of Daegu after a 61-year-old woman known as “Patient 31” who attended services there tested positive, the Korea Centres for Disease Control and Prevention (KCDC) said.

It also reported the seventh and eighth deaths from the disease in the country, both from a hospital in Cheongdo, a county where confirmed cases surged in recent weeks, along with nearby Daegu.

“If we cannot block the spread in the Daegu region in an effective way, there are high possibilities it would lead to a nationwide transmission,” Vice Health Minister Kim Kang-lip told a regular briefing.

Almost all major cities and provinces reported some infections. Authorities are still investigating the exact cause of the new outbreak, with Patient 31 having no recent record of overseas travel.

Kim said the government had ordered self-quarantines and was testing about 9,500 people who joined services at a Daegu branch of the Shincheonji Church of Jesus, also known as the Temple of the Tabernacle of the Testimony, attended by Patient 31.

When raising its alert level on Sunday, South Korea vowed to rein in public activities and provide extra resources for Daegu and Cheongdo, designated last week as “special care zones”.

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President Moon Jae-in said the government should start reviewing the need for a supplementary budget to blunt the impact of the coronavirus outbreak on Asia’s fourth-largest economy.

“In addition to swiftly deploying the emergency fund set aside, the government should review drafting of a supplementary budget,” Moon told chief aides and medical experts at a meeting.

The U.S. military command raised its risk level to high on Monday, after the widow of a former soldier who lives in Daegu and had access to a base supermarket tested positive for the virus, the first infection connected to the force stationed in South Korea.

In Daegu and elsewhere, citizens flocked to supermarkets and pharmacies to buy surgical masks and supplies, with media showing images of hundreds lining up in front of E-Mart stores in Daegu from as early as 8 a.m.

Political and cultural events set for this week have been canceled, and the culture ministry said on Monday 24 national museums and libraries will temporarily close.

The National Assembly canceled a plenary session on Monday and called off a session on Thursday to question the government, after at least three lawmakers were checked following contact with an education official who tested positive for the virus.