South Korea's new coronavirus cases stayed above 1,000 for a second straight day Wednesday and variant cases rose to five as the government is mulling the toughest distancing rules to curb the pandemic.

The country added 1,050 more COVID-19 cases, including 1,025 locally transmitted infections, bringing the total caseload to 59,773, according to the Korea Disease Control and Prevention Agency (KDCA).

The daily infections fell slightly from 1,046 cases a day earlier amid the stricter Level 2.5 virus curbs in the greater Seoul area, which were extended earlier by one week until Sunday.

South Korea's daily cases have hovered around 1,000 for the past week due mainly to mass cluster infections.

Twenty people have died from COVID-19 in the past 24 hours, raising the death toll to 879, with the fatality rate of 1.47 percent.

Adding woes to the country's battle against the pandemic, the KDCA confirmed two coronavirus variant cases, bringing the Britain-originated virus cases to five.

The health agency on Monday confirmed a new, potentially more transmissible coronavirus variant from three people who arrived from Britain last Tuesday.

The government said it will suspend all flights from London to Incheon until Jan. 7 to prevent the virus variant from spreading in Korea, while making all incoming passengers from Britain and South Africa submit documents that prove they tested negative for COVID-19.

The government has vowed to accelerate the launch of the vaccination program after detecting the virus variant from Britain.

It plans to start its vaccination in February, with health workers and vulnerable people first in line.

US biotech firm Moderna has agreed to supply COVID-19 vaccine doses for 20 million people to South Korea during a phone conversation between President Moon Jae-in and Moderna Chief Executive Stephane Bancel, the presidential office said Tuesday.

With the deal, South Korea expects to be able to secure enough doses for its 52 million people by the end of next year.

On Sunday, the KDCA extended the current Level 2.5 distancing measures in the greater Seoul area and the Level 2 restrictions in the rest of the country until Jan. 3 on concerns over the impact on the economy.

Health authorities will decide whether to raise the social distancing measures to Level 3, the highest in the five-tier scheme, before the extended deadline.

Instead of applying measures that would deal a heavy blow to millions of small merchants, health authorities have deployed "targeted" virus curbs.

Since last Wednesday, the greater Seoul area has banned gatherings of five or more people. Restaurants in the greater Seoul area face a fine if they allow gatherings of more than four people. The strongest-ever measures have been applied nationwide since last Thursday as well.

Ski resorts and famous tourism venues were shut down to slow the spread of the virus during the Christmas and New Year's holiday season.

The third wave of the pandemic is raging across the nation. Of the newly identified local infections, about 70 percent of Wednesday's cases were reported in the capital and the surrounding areas.

Of the local infections, 383 cases were reported in Seoul and 274 cases in Gyeonggi Province that surrounds the capital. Incheon, west of Seoul, reported 48 more cases.

Other municipalities reported new infections, with the country's third-biggest city of Daegu adding 49 cases and North Chungcheong Province reporting 45 new cases.

The number of seriously or critically ill COVID-19 patients reached 332, up from 330 a day earlier.

The total number of people released from quarantine after making full recoveries stood at 41,435, up 732 from the previous day. (Yonhap)