Passengers heading to Seoul wait to board a KTX train at Gwangju-Songjeong Station on the last day of this year's Seollal holiday on Jan. 24. Yonhap

Korail and SR, operators of South Korea's two fastest railway services, have introduced plans to address an expected surge in seat cancellations with one of the country's major holidays approaching in less than a week, the state-run railways said Sunday.

Records show that no-shows for Korail's KTX and SR's SRT services have been more frequent during Chuseok later this month and Seollal (Lunar New Year), Korea's two major holidays.

To ensure their trains remain as fully booked as possible, the companies are either looking to boost sales of returned seats or increase cancellation penalties.

Their measures come as seat cancellations for KTX and SRT have been consistently more frequent around the two holidays.

According to Rep. Yoon Jong-kun of the main opposition Democratic Party of Korea, who is also a member of the National Assembly's Land, Infrastructure and Transport Committee, 41 percent of KTX seats booked during the two holidays from 2019 to this year were returned.

On average each year, out of 3.31 million seats booked ahead of the holidays, over 1.35 million are returned. For SRT, the cancellation rate during this period stands at 15 percent.

Korail saw a seriously high no-show rate last Seollal. Out of 4.08 million booked seats, 46 percent were returned. Among the returned seats, 195,000 seats remained unsold and empty until the train departed.

SR, during the same period, sold 690,000 seats but saw 14 percent of the tickets returned. Among the returned seats, 54,000 remained unsold.

"Canceling seats seconds before the train leaves or after it departs is no less than dumping the seats," Yoon said. "The operators will have to either raise their cancellation penalties or find ways to resell the returned seats, especially during holidays."

To counter the issue, Korail is slashing 30 percent off its seat prices and offering an extra discount for family travelers during the upcoming Chuseok holiday.

SR is also offering up to 40 percent discount for its seats. SR, moreover, has partnered with Danggeun, Bunjang and Joonggonara, the country's major online trading platforms for second-hand items, to preemptively nab illegal trades of purchased seats.