North Korea's leader Kim Jong-un (left) signs the guest book next to his sister Kim Yo-jong (right) during the Inter-Korean summit with South Korea's President Moon Jae-in (not pictured) at the Peace House building on the southern side of the truce village of Panmunjom on April 27, 2018. (AFP)

Signs that North Korea has been dismantling part of a western inter-Korean railway have been detected, Seoul's defense ministry said Thursday, the latest in Pyongyang's apparent move to eliminate routes once seen as symbols of inter-Korean exchange and cooperation.

The military has detected the North removing ties and rails on the northern side of the Gyeongui line that connects the military demarcation line to the North Korean border city of Kaesong since late June, according to the ministry.

The move is the latest in the North's push to demolish inter-Korean routes after its leader Kim Jong-un gave instructions for "strict" measures to block all the channels of inter-Korean communication along the border on the North's side to an "irretrievable level" in January.

In the following months, the North installed mines and removed street lamps along two rare roads connecting the two Korea -- the Gyeongui road, which connects the South's western border city of Paju to the North's Kaesong, and the Donghae road along the east coast -- in recent months.

Last month, the national spy agency said it detected signs of North Korea demolishing some sections on the northern side of the Donghae railway.

The North has also been deploying large numbers of troops in front-line areas since April to conduct an array of activities, such as planting mines, erecting walls and building roads for military operations.

Former liberal President Moon Jae-in and Kim agreed to connect and modernize the two railways during the summit at the truce village of Panmunjom in April 2018.

But the project has effectively fell through since the 2019 no-deal Hanoi summit between then U.S. President Donald Trump and Kim.