Transmission routes for three out of 10 people diagnosed with COVID-19 in South Korea in recent days remain unknown, as quarantine authorities deal with an unrelenting wave of cases in the nation. 

The Korea Disease Control and Prevention Agency(KDCA) said on Monday the portion of COVID-19 cases with untraceable transmission sources has reached yet another record high of 29-point-six percent. 

According to the agency, among the nine-thousand-246 new cases in the past two weeks, two-thousand-739 were categorized as such "silent transmissions". 

It is the highest since related data began to be compiled in April of last year. 

The figure climbed above 29 percent for the first time last Thursday before edging down to the 28-percent range for the following three days.