British microcomputers were among more than 100,000 foreign-made parts contained in Russian missiles and drones used in Sunday's deadly strikes on Ukraine, Volodymyr Zelensky has said.
The Ukrainian president called for further "effective" sanctions after saying parts originating in allied countries including Germany, Japan and the US have been identified in Russian weapons.
The Department for Business and Trade (DBT) said it had recently undertaken efforts to crack down on UK firms whose products have continued to make their way into Russia's military supply chain.
"We take reports of goods from UK companies being found in Russian weaponry incredibly seriously," a government spokesperson said.
The spokesperson said the government had "banned the export of thousands of goods to Russia including every battlefield item Ukraine has brought to our attention," adding that they have imposed "the most severe package of sanctions".