The UK has given UN experts satellite images of North Korean cargo shipments to Russia, the The Guardian reports.
North Korea has allegedly supplied the Kremlin with ballistic missiles and hundreds of thousands of artillery shells following Vladimir Putin's visit to the country last year.
An unpublished UK defence intelligence report seen by The Guardian shows images of three Russian ships loading cargo at North Korea's Najin port.
The images were taken between September and December.
They will now be examined by a UN panel of experts, with a report expected next month.
It could also trigger a full investigation into Russia and North Korea's breaking of international sanctions.
"Russia's use of North Korean weapons in Ukraine is a violation of multiple UN security council resolutions," a UN diplomat said.
"It undermines international efforts to prevent the spread of nuclear weapons and exposes just how desperate Russia has become in its failed invasion."
