North Korea has started sending artillery to Russia as Moscow continues its war in Ukraine, a US broadcaster reported Thursday, after last month's summit between the two countries reinforced concerns about a potential bilateral arms deal.

Citing an unnamed US official, CBS reported on the apparent arms transfer that came in the wake of a rare summit between North Korean leader Kim Jong-un and Russian President Vladimir Putin at the Vostochny Cosmodrome, a Russian spaceport last month.

The summit raised speculation that it might have led to a deal feared to help advance North Korea's efforts to build spy satellites and other weapons and in return prop up Russia's war in Ukraine.

"It was not immediately clear whether the transfer is part of a new, long-term supply chain or a more limited consignment, or what North Korea is getting in return for the weapons," the report said.

Seoul and Washington have criticized any possible transfer of arms between Pyongyang and Moscow, warning they would flout multiple UN Security Council resolutions, which Russia itself voted for. (Yonhap)