PAJU (South Korea) • The 15 ballet students groaned as they strained to do splits and laughed with relief after the teacher counted to five and let them relax.

Once a week, a group of South Korean soldiers near the Demilitarised Zone (DMZ) that divides the Korean peninsula trade army boots for ballet shoes in a class intended to ease the stress of guarding the world's most heavily fortified border.

"There's a lot of tension here since we live in the unit on the front line, which makes me feel insecure at times," said 23-year-old sergeant Kim Joo Hyeok, who is doing his mandatory military service. "But through ballet, I am able to stay calm and find balance as well as build friendships with my fellow soldiers." Mr Kim is into his second year of ballet classes and plans to continue after he is discharged from the army.

Wearing shorts, T-shirts and dance slippers, members of the army's 25th Division are taught each week by a ballerina from the Korean National Ballet under a programme that began last year and has already included a performance of Tchaikovsky's Swan Lake.

Most of the students at a recent session were first-timers. "Being in the army itself can be difficult, so I wasn't sure what kind of help I could be here," said Ms Lee Hyang-jo, a ballerina at the Korean National Ballet who visits the base once a week to train the soldiers.

"But as the soldiers learn ballet little by little, they laugh more and have a great time and seeing that makes me think that coming here is worthwhile."

As the suntanned, crew-cut dancers practised movements like the splay-kneed plie to classical music, outside the studio, another group of soldiers played soccer. But ballet toughens you up too," said Lieutenant- Colonel Heo Tae Sun.

"Ballet requires a great amount of physical strength and is very good for strengthening muscle, increasing flexibility and correcting posture."

REUTERS