British officials have revived Cold War emergency plans to relocate the royal family if there are riots in London if Britain suffers a disruptive departure from the European Union next month.

Brexit date is March 29, and there are some fears of civil unrest.

Among the "worst case" scenarios, the Mail on Sunday reported that Whitehall contingency plans include moving the Royals to safe locations away from the capital.

Pro-Brexit protesters in central London outside Buckingham Palace. Photo / Getty Images

Officials in the Civil Contingencies Secretariat, the Government department responsible for emergency planning, have "repurposed" a secret operation under which the Royals could have been accommodated in various country houses to protect them from enemy forces during the Cold War.

The reports were also echoed by The Sunday Times, who spoke with ex-police officer Dai Davies who was once in charge of royal protection.

He was quoted as saying that you would “clearly” remove the royals away from key sites if there were to be difficulties in London.

The plan has drawn criticism by leading Brexiteer Jacob Rees-Mogg, who described it as a "wartime fantasy", the Mail on Sunday reported.

"The over-excited officials who have dreamt up this nonsense are clearly more students of fantasy than of history," Rees-Mogg said.

"The Monarch's place is always in the capital, as the late Queen Mother, wife of George VI, made very clear during the Blitz.'

A source in the Secretariat said that the most extreme No Deal crisis scenario envisaged riots breaking out in London as shops ran short of staple foods.

The source claimed that the plan had been moved up their "priority list".

The source said: "As the Queen has been dragged into some of the politics around all this, it becomes more likely that she and her family could be targeted by protesters."

Neither Buckingham Palace nor Downing Street would comment yesterday, citing security concerns, but a senior Government source said: "It is not project fear. There are dozens of contingency planners whose job is to envisage every possible eventuality. They would be negligent if they didn't include the Royals in that, however far-fetched the scenario might seem."