"Actions are more important than words," Unification Ministry spokesman Kim Hyung-Seok said of the offer contained in a letter delivered Friday by an envoy of North Korean leader Kim Jong-Un to Chinese President Xi Jinping.
Chinese state media said the letter cited the North's willingness to resume stalled six-party talks on denuclearisation involving China, the two Koreas, the United States, Russia and Japan.
The reported message was greeted with scepticism in South Korea, where observers saw it as an effort to appease Beijing, rather than a genuine signal of intent.
North Korea has repeatedly declared that its programme to develop a viable nuclear deterrent is not open to negotiation.
Seoul and Washington, meanwhile, insist that the North must demonstrate its commitment to abandoning its nuclear weapons programme in order for formal talks to begin.
The North Korean state media's coverage of envoy Choe Ryong-Hae's visit to China made no mention whatsoever of a dialogue proposal.