North Korea Wednesday expressed "regrets" over the deaths of several South Koreans caused by its abrupt discharge of dam water last month.
South Korea accepted the expression as a de facto apology.
The remarks came during working-level talks between the two Koreas on flood control measures on a river that runs across their border.
The North also expressed "deep condolences" to the families of the six victims at the inter-Korean talks held at Gaeseong, a town just north of the border, an official from South Korea's Unification Ministry said at a background briefing.
"Literally speaking, the North expressed regrets and condolences," the official was quoted as saying. "But in the general context, we think it's an apology by North Korea with regard to this incident."
The victims were camping or fishing along the mouth of the Imjin River when North Korea opened its Hwanggam Dam at the upstream without notice at predawn hours.
While there have been unannounced dam discharges almost every year, this year's was the first to claim human lives.
South Korea has demanded a thorough explanation and an official apology. Seoul is also trying at the talks to make a warning call system mandatory for the North.
In explaining the reason for the abrupt discharge, the North said it "had no other choice but to urgently unleash the dam water to prevent bigger damage," the official said. Further details were not yet available, with the one-day talks set to resume later in the afternoon after a lunch break.
Wednesday's dialogue was the latest sign that the Koreas were maintaining the momentum for dialogue despite the North's short-range missile tests earlier this week. Both Seoul and Washington reacted calmly to the tests and asserted that diplomacy with the North would continue.
South Korea proposed the talks on flood control Monday, along with another set of talks on reunions for separated families, and the acceptance of both offers came the following day.
The Koreas will meet again on Friday to continue reunions for families separated by the 1950-53 Korean War. The talks will draw keen attention as to whether Seoul will decide to resume rice aid to the North in return for the humanitarian event.