Soldiers from the two Koreas guard the border between them

The talks in the truce village of Panmunjom inside the demilitarised zone are aimed at easing military tension and boosting trade.

North Korea effectively upgraded the talks last week by asking for two-star generals to attend instead of one-star.

The South is expected to put naval security high on the agenda.

Opening the talks, Northern chief negotiator Lt Gen Kim Young Chul called for unity and cooperation to fight "foreign powers" - a reference commonly used by Pyongyang to refer to the United States, the South's chief ally.

Maj Gen Han Min-koo, the South's chief delegate, said he expected "a lot of things" would be "solved well" at the talks.

Deadly clashes

South Korea is anxious to prevent clashes at sea and to establish a joint fishing area in the disputed Yellow Sea.

Deadly naval clashes between the two sides have occurred in the area and navy ships from both sides have found it increasingly difficult to patrol.

Chinese boats have been aggressively fishing in the buffer zone dividing the sea border.

The South Korean delegation is also requesting discussions on safe passage guarantees for those using cross-border roads and railways.

Although tracks have been laid connecting the two countries, trains have not passed through the military border due to the absence of this guarantee.