Britain froze the assets of Russia's Gazprombank and Alfa Bank, and the state-run shipping firm Sovcomflot FLOT.MM, in its latest round of sanctions announced on Thursday.
They were among 59 individuals and entities added to the sanctions list which has been used to target Moscow since Russia invaded Ukraine.
Gazprombank is one of main channels for payments for Russian oil and gas.
Alfa-Bank is one of Russia's top private lenders, controlled by Mikhail Fridman, who was sanctioned by Britain earlier this month, and his partners.
Among the individuals sanctioned were oil tycoon Evgeny Shvidler, founder of Tinkoff bank Oleg Tinkov and German Gref, the CEO of Russia’s largest bank Sberbank, the Foreign office said.
Britain said it was also targeting Polina Kovaleva, who it said was the stepdaughter of Russia's foreign minister Sergei Lavrov. The government said she reportedly owns a 4 million pound property in London.
"Putin should be under no illusions – we are united with our allies and will keep tightening the screw on the Russian economy to help ensure he fails in Ukraine," Foreign Secretary Liz truss said. "There will be no let-up”.
The sanctions also targeted Russian Railways, and defense company Kronshtadt, the main producer of Russian drones. Private military contractor Wagner Group has also been sanctioned.
(Reuters - Reporting by William James and Muvija M; Editing by Kate Holton)
