Ukraine on Friday urged the West to "get serious" about curbing Russia's arms production by shutting loopholes that allow it to keep sourcing critical components for weapons.
Western countries have sanctioned swathes of Russia's arms industry and banned the export of military goods and parts.
But Kyiv says Russia is still getting hold of key components made by Western firms.
"The West must get serious about strangling Russia's ability to produce weapons," Ukrainian Foreign Minister Dmytro Kuleba said in a post on social media.
"According to some data, up to 95% of the foreign-produced critical components found in Russian weapons destroyed in Ukraine come from Western countries," he said.
Kuleba claimed that private firms are exporting civilian or so-called "dual use" goods containing parts that can be used for arms.
He did not provide evidence for the claim, but Kyiv regularly disassembles Russian missiles and drones that fall on its territory to analyze their components.
Russia fires dozens of high-tech missiles and drones at Ukraine nearly every week. Iran has supplied Moscow with drones, while Western intelligence says North Korea is sending artillery shells and rockets.
Moscow has also ramped up its domestic arms production, and Kyiv has recently stepped up its calls to ensure Western goods do not find their way into Russian weapons factories.
"Ukraine would require less assistance and would lose fewer lives if all of the murky schemes and sanction evasion loopholes were thoroughly tracked down and completely closed," Kuleba said.
Speaking in Davos at the World Economic Forum earlier this week, President Volodymyr Zelensky said the West needed to "ensure that sanctions work 100%."
Ukraine is also facing its own shortage of ammunition, officials in Kyiv have admitted.
There are concerns that the West's multibillion-dollar military aid could be cut amid domestic political wrangling in both Europe and the United States.
