North Korea says it has never sold weapons to Russia and has no plans to do so, following US reports that Moscow was turning to Pyongyang to replenish stockpiles.
US officials had said that Russia was in the process of purchasing rockets and artillery shells from North Korea.
They said such moves, along with alleged purchases of Iranian weapons, showed Western sanctions were impeding Russia's efforts in the Ukraine war.
Moscow denied the reports at the time.
Any arms movement between the two countries would be in violation of United Nations sanctions.
On Thursday, in a statement carried by North Korean state media KCNA, an unnamed official at North Korea's defence ministry said: "We have never exported weapons or ammunition to Russia before and we will not plan to export them."
It accused the US, and other "hostile forces", of spreading rumours to "pursue its base political and military aims".
In early September, a US state department spokesman said Russia's North Korean purchases "could include literally millions of rounds, rockets and artillery shells."
But National Security Council spokesman John Kirby later appeared to caveat that statement, by saying the purchases had not yet been completed and there was no evidence to suggest the weapons would be used in the Ukraine war.