South Korea will launch an ecological survey on the Han River's estuary along the inter-Korean border this week as part of efforts to implement an agreement with North Korea to jointly use the now-restricted waterway, the unification ministry said Sunday.

The survey will start Monday for a 10-month run on about 80 square kilometers of wetland on the southern side of the Han River, near the western border between the two Koreas, to collect "in-depth" ecological and environmental data, according to the ministry.

"The estuary of the Han River has world-class value as an eco-belt between fresh water and seawater that has preserved outstanding biodiversity uninterrupted by human beings for a long time," the ministry said. "But it has been hard to figure out detailed conditions since it is located near the inter-Korean border."

"The government will use the survey as a chance for preservation of the bio system and peaceful use of the area between the two Koreas and will continue to make such efforts going forward," the ministry added.

Under a military agreement signed at a 2018 summit between President Moon Jae-in and North Korean leader Kim Jong-un, the two sides agreed on the joint use of the Han River estuary along their western border and conducted joint waterway research in November that year.

The border waterway has been off limits to civilian vessels due to military tensions. The inter-Korean deal calls for opening it for civilian passage so as to reduce tensions between the two sides.

The two Koreas conducted their joint survey on the waterway in late 2018 for the first time since the end of the 1950-53 Korea War.

The project, however, has stalled since the second summit between US President Donald Trump and North Korean leader Kim Jong-un ended without an agreement in February last year, bringing inter-Korean relations grounding to a halt as well. (Yonhap)