Ukrainian soldiers were observed using North Korean rockets that they said were seized by a "friendly" country before being delivered to Ukraine, the Financial Times reported on Saturday.
Ukraine's defense ministry suggested the arms were captured from the Russians, the newspaper said.
The United States has accused North Korea of providing arms to Russia, including alleged shipments by sea, but has not offered proof and North Korean weapons have not been widely observed on the battlefields in Ukraine.
North Korea and Russia deny conducting arms transactions.
The North Korean weapons were shown by Ukrainian troops operating Soviet-era Grad multiple-launch rocket systems near the destroyed eastern city of Bakhmut, site of lengthy brutal fighting, the report said.
North Korean-Russian relations
Russia's Defense Minister Sergei Shoigu made a rare visit to Pyongyang this week to celebrate the 70th anniversary of the end of the Korean War, the first visit by Moscow's top defense official since the 1991 break-up of the Soviet Union.
During the visit, Shoigu was photographed viewing banned North Korean ballistic missiles with leader Kim Jong Un at a military expo in Pyongyang, signaling deeper ties between the two countries as they each face off with the United States.