In a statement, the White House said: "Mr Scaramucci felt it was best to give Chief of Staff John Kelly a clean slate and the ability to build his own team. We wish him all the best."

Mr Kelly, the widely-respected former retired US Marine Corps general and former commander of United States Southern Command, was sworn in as chief of staff on Monday.

'There's a new sheriff in town'

The speed with which he apparently brought about the removal of Mr Scaramucci suggested he was keen to assert order quickly.