The U.K. has sanctioned a steel and mining company whose biggest shareholder is billionaire Roman Abramovich as the West continues to financially punish Russia for its invasion of Ukraine.

The U.K. announced the sanctions against Evraz, a major producer of steel products for Russia’s rail industry, including wheels and tracks, on May 5.

Evraz’s products are critical for Russia’s war effort as it uses rail to move key military supplies and troops to the front line in Ukraine.

“The steel manufacturing and mining company operates in sectors of strategic significance to the government of Russia,” the U.K. government said in a statement. “Today’s asset freeze means no U.K. citizen or company can do business with them.”

Shares in Evraz, which trade on the London Stock Exchange, have been suspended from trading since March 10, when Britain imposed sanctions on Abramovich, a tycoon believed to be close to Russian President Vladimir Putin.