North Korea on Wednesday denounced Seoul's refusal of its demand for a joint investigation into three drones found in South Korea, saying a preliminary result that pointed at Pyongyang's involvement is a "malicious slander."

South Korea's defense ministry last week said the drones recently discovered in inter-Korean border areas were produced and sent by North Korea for spying purposes, though the conclusive evidence has yet to be found.

On Tuesday, the North's powerful National Defense Commission accused South Korea of fabricating the latest case to shift the responsibility for the current heightened tensions on the Korean Peninsula, calling for a joint probe to clarify suspicions surrounding the small unmanned aerial vehicles.

Seoul's defense ministry rejected the North's offer, which it saw as a "mean psychological tactic to divide South Korea," saying the investigation team has recently teamed up with American professionals to restore their global positioning system data to find the smoking gun in the case.

On Wednesday, Uriminzokkiri, North Korea's Internet-based propaganda website, slammed the remark as "sophistry" and "malicious slandering," urging Seoul to accept its demand for a joint probe.

"South Korea has blamed us (North Korea) whenever an incident broke out, which is a routine tactic to create North-South confrontation. It clearly hampers peace and stability on the Korean Peninsula," Uriminzokiri said. "We will never accept those who push for anti-North Korean policy whoever the person is."

The latest response comes after North Korea on Monday warned South Korea it would pay a "dear price" for recent criticisms of Pyongyang's nuclear program and political system, saying they violated their no-slander agreement.

Under an agreement reached during high-level talks in February, the two Koreas had agreed to cease exchanging verbal insults to improve bilateral ties. (Yonhap)