South Korea on Thursday dismissed a claim by the Democratic People's Republic of Korea (DPRK) that it did not fire artillery shells into waters near a western sea border a day ago.

On Wednesday, South Korea fired shots in response to what it said was a sound of artillery shells presumably fired by the DPRK, one of which fell near the disputed maritime border Pyongyang refuses to acknowledge.

Pyongyang later claimed through its state media that what Seoul heard was an explosion at a construction site, but the defense ministry here told Xinhua on Thursday such an ungrounded claim is "not worthy of a response."

The maritime border in question was the scene of a deadly exchange of fire last November between the two Koreas. The incident, which Pyongyang said was provoked by a military drill between Seoul and Washington, killed four South Koreans.