Opposition leader Lee Jae-myung on Friday urged North Korea to retract its recent move to cut off all roads and railways connected to South Korea, voicing concerns over the North's "explicit intent" to completely sever inter-Korean ties.

On Wednesday, North Korea's military said it will "permanently shut off and block the southern border" with South Korea by cutting off all roads and rail links with the South and building frontline defense structures.

"We demand the immediate withdrawal of any attempts to fortify areas along the Military Demarcation Line," Lee of the main opposition Democratic Party said at a supreme council meeting. "It is deeply concerning that (the North) has revealed its explicit intent to completely sever inter-Korean ties."

Lee called on Pyongyang to "realize there is nothing to be gained from staging provocations" and to immediately stop sending trash-filled balloons to the South.

He also said the two Koreas can never become two separate countries, stressing that "brothers who share blood cannot become strangers to one another."

The Koreas are connected by road and railway along the Gyeongui line, which connects the South's western border city of Paju to the North's Kaesong, and the Donghae line along the east coast.

Since North Korean leader Kim Jong-un characterized the Koreas as "two hostile states" late last year, the North has taken steps to eliminate routes once seen as symbols of inter-Korean exchange and cooperation, including by installing mines along the Gyeongui and Donghae roads in January. (Yonhap)