The trains, which will run six times a day, are decorated with imagery connected to Pyeongchang 2018.

It includes images of Olympic Games mascot Soohorang and graphics depicting venues such as the Alpensia Ski Jumping Centre and nearby Sliding Centre.

The subway trains also show pictures of Pyeongchang 2018 merchandise, such as hats and gloves.

They will run on the Subway Line 2, a circular line which is Seoul's most heavily-used line and contains one of the longest subway loops in the world.

The unveiling of the themed trains comes as part of a concerted effort from organisers of next year's Olympic and Paralympic Games and the South Korean Government to raise awareness and promote the event across the country.

Pyeongchang 2018 have vowed to continue their promotional activities prior to the Opening Ceremony of the OIympics on February 9.

"We planned the theme train to publicise the boom and promote the boom in the people's daily life," Pyeongchang 2018 said in a statement reported by the Yonhap news agency.

"We will continue to meet more people through various public relations activities using official products."

It comes after the tickets for the Korea Train eXpress (KTX) line from Seoul to Pyeongchang went on sale earlier this month.

For those planning to use the train to travel to next year's Winter Olympic and Paralympic Games, tickets will be available to purchase one month prior to intended travel dates.

During Pyeongchang 2018, KTX will transport up to 20,910 passengers each day from Incheon International Airport to Jinbu and Gangneung Stations, it is claimed. 

It will take one hour 50 minutes from Incheon International Airport but will only operate between February 1 and 28 for the Olympic Games.