LONDON — The U.K. is imposing fresh sanctions on up to 100 vessels accused of shipping Russian oil in the face of international sanctions, British Prime Minister Keir Starmer announced Friday.

The British government said the tankers had moved more than £18 billion of Russian oil since the start of 2024 in defiance of curbs imposed on Moscow after its full-scale invasion of Ukraine in 2022.

Russia has tried getting around these economic conditions by building up a “shadow fleet” of tankers, often aging vessels with obscure ownership and unknown insurance.

Speaking ahead of a Joint Expeditionary Force (JEF) meeting in Oslo, Starmer said the move would increase pressure on Moscow.

“The threat from Russia to our national security cannot be underestimated,” Starmer said Friday. “That is why we will do everything in our power to destroy his shadow fleet operation, starve his war machine of oil revenues and protect the subsea infrastructure that we rely on for our everyday lives.”

The package of measures will also take aim at ships and boats accused of damaging critical undersea infrastructure. The sanctioned tankers will be prevented from entering British ports and risk being detained in U.K. waters. Similar curbs were imposed on the Kremlin during the last JEF meeting in December 2024.