South Korea's Defense Ministry says one North Korean coastal artillery gunport has yet to be covered despite the previous day's implementation of an inter-Korean military agreement.

It belongs to one of four coastal artillery guns deployed in the Gaemeori region in North Korea's Hwanghae Province.

South Korean military officials say the gunport is probably broken. 

A ministry official told reporters that the South has been in contact with the North on the matter, and that North Korea's military has promised to take necessary action.