Five more cases of highly infectious omicron sub-variant, BA.2.12.1, have been reported in South Korea, bringing the total caseload in the nation to six. 

The Korea Disease Control and Prevention Agency(KDCA) on Tuesday announced the newly detected infections, adding epidemiology surveys are underway to find possible additional cases. 

A person arriving from the U.S. on May 16 was confirmed to be the country's first BA.2.12.1 case the next day, while five additional cases, also arrivals from the U.S., were registered between April 18 and April 28. 

The sub-lineage, BA.2.12.1, which was first detected in the U.S. last December, is believed to be around 20 percent more transmissible than BA.2, also known as the stealth omicron. 

The BA.2 is 30 percent more infectious than the ordinary omicron variant.