South Korea's health authorities said Tuesday they have identified 26 more cases of COVID-19 variants, vowing to step up monitoring on foreign arrivals to better detect potential cases.

The Korea Disease Control and Prevention Agency (KDCA) said 24 people were confirmed to have been infected with the variant from Britain, while one person was infected with the South African variant and another with the one from Brazil.

Among them, four were domestically infected cases after coming in contact with their relatives from abroad, the KDCA said.

Authorities warned of the further spread of more transmissible viruses in the nation, saying they will expand the analysis of variant cases and tighten the monitoring of foreign arrivals.

"Those who recently arrived from abroad should pay extra caution during their self-isolation period to reduce risks of variant cases spreading in local communities," the KDCA said.

The authorities have said they remain vigilant against the possibility that highly transmissible 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 Feb. 11 to block the new virus variant that was first identified in Britain.

The KDCA has conducted further tests, known as next-generation sequencing, on arrivals from Britain and South Africa. The method provides an effective way to identify coronavirus strains and other pathogens without prior knowledge of the organisms.

Also, all foreign entrants must present papers showing negative polymerase chain reaction tests taken within 72 hours of their departure for South Korea.

The country added 303 more cases Tuesday, raising the total caseload to 81,487, according to the KDCA. (Yonhap)