North Korea troop ‘casualties’ reported after landmine explosions in DMZ

South Korean soldiers patrol the DMZ in a file photo. Troops from North Korea were reportedly injured after landmines exploded near the border. Photograph: Ahn Young-joon/AP

North Korea’s military has suffered “multiple casualties” after landmines exploded in the heavily armed border that separates the country from South Korea, local media reported on Tuesday.

The explosions in the demilitarised zone (DMZ) were reported just hours before the Russian president, Vladimir Putin, was due to visit the North Korean capital, Pyongyang, for the first time since 2000.

South Korea’s Yonhap news agency referred to “casualties” caused by landmine explosions, while the NK News website quoted the military as saying several soldiers had been “maimed or killed”.

In what appears to be an unrelated incident, dozens of North Korean soldiers briefly crossed the border on Tuesday for the second time in less than two weeks, but retreated after warning shots were fired, the South Korean Joint Chiefs of Staff (JCS) said.

The DMZ has separated the two Koreas since their 1950-53 conflict ended in a truce, but not a peace treaty.

The 4km (2.5-mile) wide strip of land bisecting the peninsula is strewn with landmines designed to deter enemy troops from making incursions that could upset the delicate decades-old standoff along the border.

The North Korean troops injured in the landmine explosions were working on creating “barren land” and laying additional mines along the border, an official from the JCS said, without revealing the date of the incident.

The soldiers had “suffering multiple casualties from repeated landmine explosion incidents during their work,” it said.

On Tuesday, an estimated 20 to 30 North Korean soldiers carrying tools crossed the Military Demarcation Line dividing the two countries on Tuesday morning, Yonhap said, citing the JCS.

The soldiers left after forces in the South fired warning shots and broadcast warnings via loudspeakers set up along the border, the JCS said, adding that the brief incursion appeared to have been accidental.

The incidents come at a time of rising tensions between Pyongyang and Seoul.

In recent weeks, the North has sent more than 1,000 balloons laden with rubbish to the South, where activists reciprocated with those containing anti-North Korean leaflets and flash drives loaded with K-pop and TV dramas.

The South also suspended a 2018 agreement designed to reduce cross-border tensions and resumed pop music and propaganda broadcasts via loudspeakers set up along the 155-mile long border.

Yonhap quoted a JCS official as saying that the border work had been carried out in locations where North Koreans had fled to the South.

“North Korea’s activities seem to be a measure to strengthen internal control, such as blocking North Korean troops and North Koreans from defecting to the South,” the JCS official said.

North Korea has deployed hundreds of troops to lay mines, build walls and reinforce roads in recent weeks, Yonhap said. Earlier this month, the South fired warning shots after North Korean soldiers briefly crossed an overgrown section of the border, apparently by accident.