South Korea's military is keeping close tabs on water levels at a dam near the inter-Korean border and is ready to step in if Pyongyang suddenly discharges water down the Imjin River, the defense ministry said Monday.

The water level at the North's Hwanggang Dam bordering South Korea has reportedly risen to near full capacity since May. An abrupt discharge of water from Hwanggang could flood South Korea's Gunnam Dam downriver.

Six South Koreans were killed in September 2009 after North Korea released a massive amount of water from the border dam without prior warning.

"(The North Korean dam's) Water level has risen up after heavy rains this year," defense ministry spokesman Moon Sang-gyun said in a regular briefing.

"Our military keeps itself informed of the issue and maintains a cooperation system with relevant government agencies," Moon said, indicating they are keeping close watch on the safety of the neighborhoods near the border region. "The military is standing ready to extend assistance if needed." 

The official said moves by the North to release water downriver from its dams cannot be labeled as some sort of "flooding attack."

Commenting on the matter, the Ministry of Unification's spokeswoman Park Soo-jin said the government hopes the North notifies the South first before any dam discharge.

"In 2009, North Korea made a pact with the South to notify each other in advance in a deal to prevent water damage in the Imjin River area," Park said. "(Seoul) expects (Pyongyang) to tell us before any dam release."

In mid-May, North Korea released water from Hwanggang Dam on two occasions without notice, driving up the water level at the Imjin River. The latest release did not result in any human damage, but some South Korean fishermen had their fishing gear swept away.

The North Korean dam is located about 42 kilometers north of the inter-Korean military demarcation line and the amount of its water reservoir is believed to be about 300 million to 400 million tons. (Yonhap)