The agreement between the nations -- which are technically still at war -- was reached at a meeting in Pyongyang last month between South Korean President Moon Jae-in and his North Korean counterpart Kim Jong Un.

The summit was the third this year between the leaders, following a rapid thaw in relations.

Both sides undertook to carry out landmine removal work at the Joint Security Area (JSA) over a 20-day period, according to the South Korean defence ministry.

A spokesman said the operation had begun on both sides, though this was not confirmed by the North.

The JSA, also known as the truce village of Panmunjom, is the only spot along the tense, 250-kilometre (155 miles) frontier where troops from the two countries stand face to face.

It is often used as a venue for talks between the two Koreas.

More than 800,000 mines are believed to have been planted along the entire border during and after the 1950-53 war to defend against infiltration.

Moon has advocated dialogue with the isolated North to nudge it toward denuclearisation.

During his summit with Kim last month, the two leaders also agreed to remove some guard posts at the border by the end of the year and halt military drills on the border from November.