LONDON - Contingency plans to deal with any widespread disorder after Britain leaves the European Union are being drawn up by senior police chiefs, it was reported Sunday in London.

The Sunday Times (ST) newspaper says a bombshell document, prepared by the National Police Co-ordination Center, outlines plans to deal with widespread civil disorder at British borders and ports in the event of a no-deal Brexit.

It adds the document warns that the necessity to call on military assistance is "a real possibility" in the weeks around Britain's departure from the EU next March.

The report says disruption and civil unrest could last for three months either side of the March 29 departure date, rather than the six weeks being planned for by the government.

The ST adds that the report is due to be discussed at an upcoming meeting of the National Police Chiefs' Council (NPCC), saying some police forces, such as Kent, are expected unilaterally to cancel rest days and leave immediately after March 29, the date Britain will leave the EU.

The area covered by Kent Police includes Britain's busiest sea port, Dover, the main link with mainland Europe.

The document warns that Operation Stack, the queuing system for heavy goods vehicles waiting to cross the English Channel when traffic is disrupted at the Port of Dover will have to be "enacted in every British seaport" requiring a heavy police commitment.

It adds, according to the ST, "If Stack is introduced across the country, the disruption to the national road network will be unprecedented and overwhelming."

The ST also claims the document also warns that a no-deal Brexit could lead to a rise in crime, particularly theft and robbery, as Britain suffers food and drug shortages with the expectation that more people will become ill.

It warns that the predominant concern for the police is that food and goods shortages, including National Health Service (NHS) supplies, will result in civil disorder leading to widespread unrest.

The NPCC lead for operations, Chief Constable Charlie Hall, told the ST: "The police are planning for all scenarios that may require a police response in the event of a no-deal Brexit. At this stage, we have no intelligence to suggest there will be an increase in crime or disorder. However, we remain vigilant and will continue to assess any threats and develop plans accordingly."

Louise Haigh, policing minister spokesperson for the main opposition Labour Party, said: "This is the nightmare scenario long feared. According to the UK's most senior police officers, a no-deal Brexit could leave Britain on the brink."

This week Prime Minister Theresa May's government will publish the final batch of the more than 80 reports on the possible consequences, and preparations for a no-deal Brexit.

In another Brexit development Sunday, Frances O'Grady, leader of Britain's biggest trades union body, the TUC, said that unless May's government struck a deal that working people need with the EU, she would demand a popular vote.

O'Grady made her comment in a television interview as trade unionists from around the country gathered in Manchester for their annual congress.

O'Grady called on May's government to extend Britain's EU membership to allow longer for negotiations, adding: "Time is running out and a crash out of the EU would be an absolute disaster for the people we represent."

One of the country's biggest unions, the GMB, has already announced support for the People's Vote campaign which is demanding a referendum on a final deal brokered between Britain and the EU.

More than 300,000 people have so-far signed the petition calling for a so-called People's Vote.

Prime Minister May has ruled out a second referendum, saying the government is determined to deliver on the 2016 referendum, in which, by a 52-48 margin, the people of Britain chose to leave the EU.