In one incident, graffiti was daubed on a wall reading: “Charles III do you know the guillotine?”

Previously, state visits by the monarch were only called off because of serious ill health or events such as the 9/11 attacks, or the war in Iraq.

Over the weekend, protesters in France were expected to continue demonstrations that have brought the country to a standstill.

The uproar over Mr Macron’s imposition of the reforms – which the government chose to push through without a parliamentary vote – has turned into the biggest domestic crisis of the president’s second term in office.

French unions have announced fresh strikes and protests for Tuesday, which would have been the second full day of the king’s state visit.

Its abrupt postponement will be considered hugely embarrassing for Mr Macron, who extended an official invitation to Charles when in London for the late queen’s funeral last September.

A presidential aide was quoted as saying in January: “It will be extremely symbolic because it will be the first official visit of Charles III. The fact that it will come before the king’s coronation shows how important France is to him.”

The late Queen Elizabeth famously placed great importance on her state visits and therefore they were seldom cancelled.

Leaked intelligence memos revealed that the French government was warned of the “high risks” of trouble in Versailles, where demonstrators were bent on “spoiling the princely moment”.

The memos said the “social risk” of unrest had rocketed to a “very high level” following Mr Macron’s television interview this week in which he stuck to his reformist guns.

Three-quarters of French workers remain unconvinced by his explanations, a poll found yesterday. Protesters had also expressed their intention to mobilise in Bordeaux where the king and queen consort were expected to visit on Tuesday.