The move was announced in a statement sent Wednesday to South Korea from North Korea's chief delegate to inter-Korean military talks.
North Korea recently cut a Red Cross hotline between the Koreas, but there's still a hotline linking aviation authorities in both Koreas.
The hotline mentioned Wednesday is important because the Koreas use it to communicate as hundreds of workers travel back and forth to the Kaesong industrial complex. Officials say more than 900 South Korean workers were in Kaesong on Wednesday.
North Korea is angry over routine U.S.-South Korean drills and recent U.N. sanctions punishing it for its Feb. 12 nuclear test.
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