The new 50p tax rate for high earners is a “tax on London”, Boris Johnson’s office said on Sunday as it issued figures showing the capital would be hit four times harder than the rest of the UK.

London’s high earners will pay an extra £5bn in taxes during the next three years, the mayor said as he intensified his calls for the abolition of the tax. Mr Johnson has taken a harder line in calling for the scrapping of the “supertax” than the Conservative party leadership.