President Trump has threatened to hit Boris Johnson with tariffs on British cars if he goes ahead with “digital tax”

Boris Johnson is risking a post-Brexit rift with President Trump as he prepares to clash with the United States over tax, trade and foreign affairs.

The prime minister is planning to push ahead with a levy on large technology companies despite the threat of a trade war with Washington.

Downing Street says that it will introduce a 2 per cent sales duty on companies such as Facebook and Google from April amid concerns that they are “undermining trust and confidence in our international system”.

Andrea Leadsom, the business secretary, told Sky News that “huge companies are making vast profits” and a new tax regime would help bring about “a level playing field” with other businesses.

Steven Mnuchin, the US Treasury secretary, said at the World