Civil unrest could last for three months either side of March 29

Police chiefs are drawing up contingency plans to deal with widespread civil disorder at the country’s borders and ports in the event of a no-deal Brexit, according to a leaked report.

The bombshell document, prepared by the National Police Co- ordination Centre, warns that the “necessity to call on military assistance is a real possibility” in the weeks around Britain’s departure from the EU.

The report, which is due to be discussed at a meeting of the National Police Chiefs’ Council (NPCC) next week, claims that “widespread leave embargoes” will be required. Some forces, such as Kent, are expected unilaterally to cancel rest days and leave immediately after March 29.

The document also warns that a no-deal Brexit could lead to a rise in crime,