Tickets for codesharing flights are cheaper to buy directly from the airline that actually flies the route than any of the partners.

"The price can be up to three times higher when buying the ticket via a codesharing partner," market researcher Consumer Research said on Thursday.

Codesharing is an agreement where two or more airlines market flights on a route only one of them actually flies. For example, Korean Air may sell tickets to China but the plane will actually be China Airlines.

But when Consumer Research compared airfares on 11 routes as of Feb. 20, it found that tickets sold on the website of Korean Air and Asiana Airlines were 54 percent more expensive than the carriers which actually operate the routes.

A flight between Incheon and Singapore showed the biggest price gap. Singapore Airlines, which operates the route, charges W515,900 on its website, but partner Asiana tries to flog it for nearly triple at W1.42 million (US$1=W1,076).

"Unlike codesharing flights, in case of direct routes, we offer competitive price options," an insider at a domestic airlines explained.

