Boris Johnson has attacked the prime minister for achieving "two thirds of diddly squat" in his pre-referendum negotiations with Brussels.

The London Mayor hit back at his critics for "crowing too soon" in his Daily Telegraph column.

Mr Johnson faced criticism after saying Mr Obama's call for Britain to remain in the EU was "incoherent", "inconsistent", and "downright hypocritical".

On his visit to the UK, Obama said being part of the European Union "enhances Britain's global leadership".