Unionized pilots of South Korea's largest flag carrier Korean Air Lines Co. went into a 10-day strike Thursday, but the company said customer inconvenience will likely remain at a minimum.

On the first day of the walkout that will last until the end of the year, 18 out of 203 Korean Air flights, including four international flights, were cancelled due to the walkout, the company said in a press release.

The four international flights cancelled included two to Japan's Narita airport and one to Osaka.

Korean Air earlier said those who have already booked such flights will be allowed to change their flight schedule or get a full refund free of charge.

"The company is making all necessary preparations to minimize inconvenience of its passengers, and to make sure there will be no gap in the safe operation of flights," it said.

Over the 10-day period ending Dec. 31, only 24 international flights, or 2 percent of the total 1,293 previously scheduled, will be cancelled due to the strike.

The domestic side might face a slightly more serious problem with 15 percent or over 111 round trips out of 741 scheduled set to be called off.

The first walkout by unionized Korean Air pilots in 11 years follows failed negotiations over a wage increase.

The workers are demanding a 34 percent pay raise, while the company refuses to budge from its offer of a 1.9 percent increase.

However, the unionized pilots have said their demand was rather symbolic, insisting their actual demand was to improve their working conditions, which, they claimed, will help enhance the overall safety of Korean Air flights.

They added the union had repeatedly expressed its intention to call off the strike had the company agreed to add even a single dollar to its initial offer, which the company refused.

There are said to be about 2,300 pilots working for Korean Air but less than 20 percent, or some 460, of them may take part in the strike under a 2010 revision to the aviation law that sought to ensure steady and safe operations of public transportation.

The labor union said only 189 pilots will take part in the strike "to help minimize passenger inconvenience and prevent the accumulation of fatigue of those who will continue to work over the period." (Yonhap)