Boris Johnson, UK prime minister. Image Credit: Bloomberg

London: The United States and Britain would seek to cut off Russian companies' access to U.S. dollars and British pounds if the Kremlin orders an invasion of Ukraine, British Prime Minister Boris Johnson told the BBC.

"The plan that we are seeing is for something that could be really the biggest war in Europe since 1945 just in terms of sheer scale," Johnson said.

Johnson said that sanctions on Russia in the event of an invasion would go much further than previously suggested in public.

He said the United Kingdom and the United States would stop Russian companies "trading in pounds and dollars" - a move that he said would "hit very very hard" with its impact, the BBC reported.