Asiana Airlines Inc., South Korea's second-biggest airline, said Monday it will increase the number of flights to Singapore starting this month as the two countries recently signed a travel bubble agreement.

A travel bubble refers to a quarantine-free travel partnership between two or more cities or countries with similar levels of COVID-19 cases.

Asiana has been operating three flights a week -- on Tuesdays, Wednesdays and Fridays -- on the Singapore route, and passengers are required to undergo a two-week mandatory quarantine in both countries.

Under the agreement, Asiana will add one flight on Saturdays starting Nov. 15 and another on Sundays beginning Dec. 1 to keep pace with increasing outbound travel demand amid the nationwide vaccination campaign, the company said in a statement.

Starting Nov. 15, those who have had two weeks elapse since their second round of vaccinations and submit negative polymerase chain reaction (PCR) test results will be exempt from the mandatory self-isolation, it said.

The quarantine-free vaccinated travel lane (VTL) will be available for flights on Tuesdays, Wednesdays, Fridays and Sundays, but the VTL won't be applied to flights on Saturdays, the company said.

"It means only fully vaccinated people who tested negative in the PCR coronavirus test will be allowed to use the VTL," a company spokesman said.

In July, the carrier resumed flights to Saipan under the travel bubble agreement. (Yonhap)