Seoul, Oct. 10 -- Asiana Airlines Inc. has reignited tensions with South Korea's low-cost carrier after resuming flights on a route from Incheon to Osaka using newly obtained slots, months after surrendering the same route to Jeju Air Co. under Japanese antitrust conditions tied to its planned merger with Korean Air Lines Co., according to a report by Pulse, the English service of Maeil Business Newspaper Korea.

"The flag carrier, which had been required to cede the route to Jeju Air as part of efforts to ease monopoly concerns, has now re-entered the market by securing new airport slots in Osaka, effectively restoring its pre-merger flight schedule," the report said.

The move has triggered a backlash from budget airlines, which accuse ...