North Korea has vowed to cut two key communication hotlines with the South, amid rising tensions after Pyongyang’s recent rocket and nuclear tests.
It comes after Seoul suspended its operations at the jointly-run Kaesong industrial complex in the North.
Kaesong is one of the last points of co-operation between the two Koreas and a key source of revenue for Pyongyang.
The North has called the shutdown “a declaration of war” and has designated Kaesong as a military zone.
Seoul says the suspension is aimed at cutting off money the North uses for nuclear and missile development.
Pyongyang carried out its fourth nuclear test last month, and launched a satellite into space on Sunday, drawing international condemnation.
North Korea said it was kicking out all South Koreans from the jointly run Kaesong industrial zone on Thursday, calling the South’s move to suspend operations, in retaliation for Sunday’s rocket launch by the North, a “declaration of war”.
The North declared the industrial park, run by the rivals as a symbol of cooperation for more than a decade, a military control zone, the agency that handles its ties with Seoul said, according to the official KCNA news agency.
Dozens of South Korean trucks were already returning across the border earlier in the day, laden with goods and equipment, after the South said it was pulling out.
“Unpardonable is the puppet group’s act of totally suspending the operation in (Kaesong), finding fault with the DPRK’s H-bomb test and launch of a satellite,” the North’s Committee for the Peaceful Reunification of Korea said, referring to South Korea.