Mandatory outdoor mask rules for those who have received their first shots of COVID-19 vaccines could be reintroduced if the country sees a rise in new coronavirus variant cases, the prime minister said Tuesday.

Starting Thursday, South Korea plans to allow people administered with their first vaccine doses to travel outdoors without masks, as part of the government's new COVID-19 guidelines emphasizing incentives for vaccinated people.

Prime Minister Kim Boo-kyum, however, stated that the government "cannot but make mask wearing rules mandatory again" in the case new COVID-19 variant cases rise, amid concerns over a steady rise in cases of the highly contagious Delta variant.

During the period from June 20-26, the number of confirmed cases of strains from Britain, South Africa, Brazil and India came to 267, bringing the cumulative number of confirmed cases of variants to 2,492, health authorities said.

"The risk in rise of contamination could only rise following the introduction of the revised social distancing guideline," Kim said at a daily interagency meeting on the government's COVID-19 response.

Kim stressed that other nations with high rate of inoculations were also tightening their COVID-19 responses again, explaining that the number of daily new patients in Britain, which dropped to as low as the 1,000 level, surged back to around 20,000.

The prime minister stated that South Korea could also see a potential surge in new cases and instructed health authorities to prepare special response measures in line with the introduction of the new guidelines in July. (Yonhap)