The government said Transneft was one of the world's largest pipeline firms and the transporter of more than 80% of Russia's crude exports. It was targeted to further cut Moscow's energy revenues.
The West has imposed tens of thousands of sanctions on Russia, including its oil sector, but has failed to bring Russian oil exports down by any significant amount. China, India and Turkey still buy Russian oil.
"The UK has today taken decisive action to disrupt the critical financing, military equipment and revenue streams that sustain Russia's aggression," foreign minister Yvette Cooper said in a statement.
UK'S LARGEST SANCTIONS PACKAGE
The new measures bring the number of people, companies and ships sanctioned under Britain's Russia measures to more than 3,000. Tuesday's package included 48 oil tankers identified as part of efforts to curb Russia's "shadow fleet."
The latest sanctions package, which Britain said was its largest since Russia's invasion of Ukraine in 2022, added subsidiaries of Russia's state nuclear agency Rosatom for their roles in supporting Moscow's nuclear energy exports.
Rosatom declined to comment.
Britain also designated Gazprom SPG Portovaya LLC, which it said was involved in Russia's liquefied natural gas shipments, and a cluster of Russian banks. Gazprom was sanctioned in January 2025 in a co-ordinated move with the United States.
Sanctions were also imposed on two television channels in Georgia which the British government accused of spreading deliberately misleading information about the war. Representatives of both channels criticised the sanctions.
REVENUE SQUEEZE ON MOSCOW
London said its sanctions were piling pressure on Russian President Vladimir Putin. But some British lawmakers say it is unclear whether sanctions are translating into tighter controls on re-exports and other forms of circumvention.
Traders and analysts expect Russian oil exports to begin to decline this year after the U.S. and the European Union imposed new sanctions on top Russian oil firm Lukoil and Rosneft and multiple tankers, but data has yet to show a drop.
Analysis by the nonprofit Centre for Research on Energy and Clean Air showed Russia earned 193 billion euros ($227 billion) from oil, gas, coal and refined products exports in the 12 months to February 24, 2026, a 27% drop from the comparable period before the invasion.
Russia's gas exports have collapsed since 2022, but sanctions have not reduced its oil export volumes. Instead, they have pushed Moscow to sell crude at lower prices.
Russia has also redirected crude to China, India and Turkey, often using the shadow fleet of ageing, uninsured tankers.
Western governments have targeted those tankers and Britain said "deterring, disrupting and degrading" them remained a priority.
Under Tuesday's package against what Britain described as Russia's dark-web oil networks, sanctions were imposed on 175 companies in the Dubai-based 2Rivers group, which the British government said was one of the world's largest shadow-fleet operators and a major trader of Russian crude.
2Rivers did not immediately respond to a request for comment.
U.S. President Donald Trump has pushed India to shift away from Russian crude as a condition of a trade deal, and the EU is debating a broader ban on business supporting Russia's seaborne crude trade.
The EU failed to agree on Monday on a new sanctions package against Russia and a huge loan for Ukraine amid a dispute over oil supplies.
(Reuters, February 24, 2026)