North Korea did not notify South Korea before discharging water from a border dam earlier this week in violation of an inter-Korean agreement, a unification ministry official said Tuesday.

On Monday, the North partially opened the floodgates of Hwanggang Dam on the western inter-Korean border and sent water into the Imjin River, a move that put authorities here on alert against the potential rise in water levels in the South.

"North Korea has opened the gates of the dam three times from July to Aug. 3. The North has not notified us in advance as it opened the gates of the dam," the ministry official said.

"The water level in Pilseung Bridge as of 7 a.m. Tuesday was 2.99 meters, and it has not reached a level of concern," he said. "The government is cooperating closely with several institutions, maintaining communication and strictly following the response system."

Under an agreement signed between the two Koreas in October 2009, the North agreed to notify the South in advance of its plans to open the floodgates, following a deadly accident that killed six South Koreans after the North discharged water from Hwanggang Dam without notice.

"The government maintains the stance that (the two Koreas) must abide by inter-Korean agreements," he said. (Yonhap)