North Korea accused South Korea of a “dangerous provocation” during a recent incident at the border of the two countries, adding to tensions as Pyongyang chafes at the annual joint US-South Korean military drills that are underway.

North Korean troops, who were working on construction and maintenance in the area, did not heed broadcasted messages to halt, an investigation said.

Pyongyang's state media call the shots a "deliberate provocation", as the South Korean leader begins visit to US and Japan.