Ukrainian forces have struck one of Russia's "most important military factories", President Volodymyr Zelensky has said.
"The plant produced electronics and components for Russian missiles. The very missiles that strike our cities, our villages and civilians," he said.
British Storm Shadow missiles were used to hit Kremniy El plant in the border region of Bryansk, Ukraine's military said.
Russian local authorities say at least six civilians were killed and 42 injured in the "terrorist missile attack". President Vladimir Putin's spokesman said it was "obvious that the launch of these missiles was impossible without British specialists".
"In order to prevent such barbaric actions by the Kyiv regime from continuing, the special military operation is being conducted," Dmitry Peskov said, using the Russian description for the full-scale invasion of Ukraine that Putin ordered on 24 February 2022.
