South Korea has identified a total of 321 cases of "emerging" variants of the novel coronavirus since December, health authorities said Tuesday.

The Korea Disease Control and Prevention Agency (KDCA) said these variants are different from the three most-known mutations from Britain, South Africa and Brazil that are known to be more transmissible.

There is no indication yet whether these new strains are more deadly than current circulating variants of the virus, the KDCA said.

Of the total, 294 are cases of the variant named 452R.V1, which was first identified in California and has been circulating in the region since December, the KDCA said.

Nine of them are cases of the variant named B.1.167 that was first detected in Maharashtra, a state in western India, the KDCA said.

The authorities have said they remain vigilant against the possibility that the new variants could spark another uptick in virus cases here.

The recent emergence of several COVID-19 mutations has complicated the global fight against the pandemic because they are more transmissible than the original one.

South Korea has extended the ban on passenger flights arriving from Britain, which has been in place since Dec. 23, until Thursday to block the new virus variant that was first identified there.

Also, all entrants, both foreigners and locals, have been required to present certificates of negative polymerase chain reaction (PCR) tests taken within 72 hours of their departure for South Korea since late February.

On Tuesday, the country reported 549 more COVID-19 cases, staying in the 500s for the second day, the KDCA said. The total caseload increased to 115,195. (Yonhap)