The fury came after Seoul expressed doubts about the sincerity of Pyongyang's repeated peace overtures, and instead sought closer military ties with Japan and longtime ally the US against threats from the North.
Regional tensions have also soared after the North in November shelled an island near its disputed maritime border with the South, killing four South Koreans, including two civilians.
On Sunday Rodong Sinmun, mouthpiece of the North's ruling Communist Party, labelled talks held on January 10 between Seoul and Tokyo's defence chiefs a "new military conspiracy" that hampered regional security by damaging inter-Korea ties.
"Japan has worked hard with bloodshot eyes to secure a legitimate pretext for its military overseas expansion," the newspaper said in an editorial carried by state media.
It also denounced Seoul for "paving the way for Japan's reinvasion" of the Korean peninsula, a reference to Japan's brutal colonial occupation from 1910-1945.
Despite the historical animosities, Japan and South Korea's defence chiefs pledged deeper cooperation and discussed signing agreements to share military secrets, potentially including those on the North's nuclear programmes.
"The recent military talks between the South and Japan will accelerate a military alliance among the US, Japan and South Korea and will create another major obstacle in inter-Korea dialogues and improving relations," Rodong Sinmun said.
It also urged Seoul to set aside "military game plays with foreign aggressors," stressing that "the door for inter-Korea talks is open."
Pyongyang, in a flurry of peace overtures since the November attack, on January 10 sent its first official proposal for talks with Seoul and said it would restore a cross-border hotline.
Seoul has rejected the proposal, saying Pyongyang's overtures are a cosmetic exercise to improve its international image and get much-needed aid.
The North also stepped up separate diplomatic charm offensive towards Japan, welcoming Tokyo's willingness to resume direct talks and saying it is "ready to meet and talk with countries that are friendly" to Pyongyang.
Pyongyang's state media last week praised Japanese Foreign Minister Seiji Maehara for hinting Tokyo may seek bilateral talks to revive the stalled six-party disarmament talks on the North's nuclear programmes.