Military talks aimed at easing high tensions between North and South Korea collapsed Wednesday when the North's delegation walked out, Seoul's defence ministry said.
It was the first cross-border dialogue since the North's deadly shelling of a South Korean island on November 23, which briefly sparked fears of war.
A ministry spokesman told AFP the North's negotiators crossed the borderline 10 minutes after walking out of the meeting. "They even failed to discuss when to meet again," he said.
"Under the current situation, we can say the talks have collapsed."
The spokesman said he had no immediate details of the cause of the breakdown. The South had been demanding an apology for two border incidents last year which killed 50 South Koreans.
Four people including civilians died in the shelling of Yeonpyeong island near the disputed Yellow Sea border. The South also accuses the North of torpedoing a warship last March with the loss of 46 lives, a charge it denies.
The working-level talks at the border village of Panmunjom had been intended to set the date and agenda for higher-level military dialogue.
"The talks collapsed over differences over the agenda for high-level talks," a defence ministry official was quoted as saying by Yonhap news agency.
A ministry official quoted by YTN television said the atmosphere "was quite charged with emotion".
Earlier Wednesday the South said it had agreed in principle to hold separate Red Cross talks on reunions for separated families. But it linked those talks to progress in the military dialogue.
The South insisted that the proposed high-level military talks discuss both the warship sinking and the shelling. It stressed that better relations would come only after the North apologises and punishes those responsible for them, a defence ministry statement said.
But the North proposed the agenda focus on "the stoppage of all military actions that can be considered as provocative acts by the other side".
The North flatly denies any involvement in the sinking of the South's warship.
It says its attack on Yeonpyeong was in response to a South Korean live-fire drill there, which dropped shells into waters claimed by the North.
The South's unification ministry said separately it has accepted in principle the North's proposal for Red Cross talks on family reunions and other humanitarian issues.
The date and venue should be agreed after the military talks are wrapped up, a spokeswoman said, reiterating the South's call for the North to take "responsible measures" over the shelling and the warship sinking.
Tens of thousands of Koreans were separated from family members during the 1950-53 war. The occasional temporary reunions bring together only a fraction of those seeking to meet loved ones.
After the island attack, the South staged a series of military drills and began fortifying its frontline islands.
The North in response warned of nuclear war, but abruptly changed tack in January and launched a series of appeals for dialogue with the South.
China, the North's ally and economic lifeline, is striving to revive six-party talks that offer the North economic and diplomatic benefits in return for nuclear disarmament.
However the United States, also a forum member along with the two Koreas, Japan and Russia, says the North must mend ties with the South before the nuclear dialogue can resume.