Britain on Tuesday sanctioned 20 ships it said were using illicit practices to avoid sanctions on Russian oil, its latest measures targeting Russia's so-called shadow fleet of vessels.
"As [Russian President Vladimir] Putin's oil revenues continue to fuel the fires of his illegal war, Ukrainian families are enduring cold, dark nights, often without heating, light or electricity, targeted by Russia's relentless missile attacks," British Prime Minister Keir Starmer said.
"These sanctions will add further pressure to Putin's stalling war economy."
The ships sanctioned include Ocean Faye, Andaman Skies, and Mianzimu, which have each carried more than 4 million barrels of Russian oil this year, Britain's government said.
The measures restrict or prohibit their movement and access to some British ports.
Britain and 11 other Western nations agreed on measures Monday to "disrupt and deter" Russia's shadow fleet.
Starmer also announced 35 million pounds ($44 million) of emergency support to help Ukraine repair its energy grid.
($1 = 0.7879 pounds)