Police are preparing for disorder at British ports in the event of a no-deal Brexit, Metropolitan Police Commissioner Cressida Dick has revealed.

The head of Scotland Yard said her force was also bracing for the loss of key European data systems that are “very important” for keeping London safe.

She said that the police were conducting careful, calm and sober contingency planning for eventualities, particularly relating to ports in Kent as well as in other parts of the UK. "Is there going to be protests, is there going to be disorder?” she asked, while addressing delegates at the Police Superintendents' Association conference in Leicester.

“At the moment in planning terms it’s a long-way off because there are so many uncertainties that could happen.”

Her comments came after a leaked document prepared by the National Police Coordination Centre revealed the “real possibility” of police calling on the military to help with civil disorder caused by a no-deal Brexit.

It warned of traffic queues at ports and said concerns around medical supplies could “feed civil disorder”, while a rise in the price of goods could also lead to “widespread protest” and trigger crimes such as theft.

Ms Dick raised additional concerns over the potential loss of access to EU systems including the European Arrest Warrant, Europol and databases containing information on criminals and terrorists entering the UK.

“At any one time in my custody suites I will have 35, 40 per cent foreign nationals, over half EU citizens and a huge chunk would have travelled through Europe,” she explained.

“The systems we have instant, automated, quick access to are very important for keeping London safe ... the reality is that, as laid out in the government’s security paper, these are very important instruments for us and if we don’t have them, whatever else we have won’t be as good and we need to make them work as quickly as we can.”

The Home Office has said it does not “want or expect a no-deal scenario” and is confident that the EU will accept a proposed security treaty that would allow continued British access to Europol, the Schengen Information System, the European Arrest Warrant and other measures.

“However, it is the duty of any responsible government to prepare for every eventuality, including the unlikely scenario that we reach March 2019 without agreeing a deal,” a spokesperson added.

“With that in mind, we are working closely with operational partners – including the police – on contingency planning so we can ensure the safety and security of our citizens in all scenarios.”

Almost 800,000 people have signed The Independent‘s petition for a final say referendum on the Brexit deal struck with the EU, which has been supported by politicians from all parties.

Contingency planning for Brexit has added to the strain police forces are already under amid a rise in the terror threat and violent crime, and the loss of 44,000 officers and staff driven by a 30 per cent cut in government funding since 2010.

A report released on Monday by the National Audit Office (NAO) warned of falling arrest rates and victim satisfaction levels.

The biggest issues facing UK on leaving EU Show all 8 1 /8 The biggest issues facing UK on leaving EU The biggest issues facing UK on leaving EU Post-Brexit immigration workers sorting radishes on a production line at a farm in Norfolk. One possible post-Brexit immigration scheme could struggle to channel workers towards less attractive roles - while another may heighten the risk of labour exploitation, a new report warns. PA The biggest issues facing UK on leaving EU Customs union A key point in the negotiations remains Britain's access to, or withdrawal from, the EU customs union. Since the referendum there has been hot debate over the meaning of Brexit: would it entail a full withdrawal from the existing agreement, known as hard Brexit, or the soft version in which we would remain part of a common customs area for most goods, as Turkey does? No 10 has so far insisted that “Brexit means Brexit” and that Britain will be leaving the customs union, but may be inclined to change its position once the potential risks to the UK’s economic outlook become clearer. Alamy The biggest issues facing UK on leaving EU Northern Ireland-Irish border Though progress was made last year, there has still been no solid agreement on whether there should be a hard border between Northern Ireland and the Republic of Ireland. To ensure borderless travel on the island, the countries must be in regulatory alignment and therefore adhere to the same rules as the customs union. In December, the Conservative Party’s coalition partners, the DUP, refused a draft agreement that would place the UK/EU border in the Irish Sea due to its potential to undermine the union. May has promised that would not be the case and has suggested that a “specific solution” would need to be found. Getty The biggest issues facing UK on leaving EU Transition period Despite protests from a small number of Conservative MPs, the Government and the EU are largely in agreement that a transitional period is needed after Brexit. The talks, however, have reached an impasse. Though May has agreed that the UK will continue to contribute to the EU budget until 2021, the PM wants to be able to select which laws made during this time the UK will have to adhere to. Chief negotiator Michel Barnier has said the UK must adopt all of the laws passed during the transition, without any input from British ministers or MEPs. EPA The biggest issues facing UK on leaving EU Rights of EU citizens living the UK The Prime Minister has promised EU citizens already living in the UK the right to live and work here after Brexit, but the rights of those who arrive after Brexit day remains unclear. May insists that those who arrive during the transition period should not be allowed to stay, whereas the EU believe the cut-off point should be later. Getty The biggest issues facing UK on leaving EU Future trade agreement (with the EU) Despite this being a key issue in negotiations, the Government has yet to lay out exactly what it wants from a trade deal with the EU. Infighting within the Cabinet has prevented a solid position from being reached, with some MPs content that "no deal is better than a bad deal" while others rally behind single market access. The EU has already confirmed that access to the single market would be impossible without the UK remaining in the customs union. Getty The biggest issues facing UK on leaving EU Future trade agreements (internationally) The Government has already begun trying to woo foreign leaders into prospective trade agreements, with various high profile state visits to China, India and Canada for May, and the now infamous invitation to US President Donald Trump to visit London. However the UK cannot make trade agreements with another country while it is still a member of the EU, and the potential loss of trade with the world's major powers is a source of anxiety for the PM. The EU has said the UK cannot secure trade deals during the transition period. EPA The biggest issues facing UK on leaving EU Financial services Banks in the UK will be hit hard regardless of the Brexit outcome. The EU has refused to give British banks passporting rights to trade within the EU, dashing hopes of a special City deal. However according to new reports Germany has suggested allowing trade on the condition that the UK continues paying into the EU budget even after the transition period. Getty

It said that the Home Office’s “light touch” approach means it does not know if the police system is financially sustainable.

Sir Amyas Morse, head of the NAO, said: “There are signs that forces are already experiencing financial strain and struggling to deliver effective services to the public.

”If the Home Office does not understand what is going on it will not be able to direct resources to where they are needed, with the risk that the situation could get worse.”

While no police force has failed financially, the report highlighted indications that the sector as a whole is ”finding it increasingly difficult to deliver an effective service”.

Ms Dick said the Met was among forces that called for a 3 per cent pay rise for officers, which was rejected by the government in its most recent settlement.

“The government chose to ignore the recommendations of the Police Remuneration Review Body and chose instead to impose 2 per cent,” she added.

“That feels like 1 per cent of our officers and I am extremely disappointed by that outcome.”

Pointing out that police officers were unable to strike, the Commissioner said the government had an “obligation to respect the carefully developed arguments of the pay body”, adding: “I am sorry to say i think that decision will have affected morale and recruitment, and it will perhaps affect retention... I’m disappointed with the decision and I feel it is a punch on the nose.”

A survey by the Police Federation, which represents more than 100,000 rank-and-file officers, recently found a record number of officers were taking second jobs to supplement their “insulting” wages.

The government has championed its frontline policing review, but it does not cover pay or demand.

Nick Hurd, the policing minister, told the conference the Home Office was in a “critical stage of negotiations with the Treasury” to increase police funding in the upcoming government-wide pay review.

Ms Dick stopped short of saying government funding cuts had caused a rise in recorded crime across England and Wales, but said it “was part of it”.

The Metropolitan Police is among forces that has introduced an “assessment policy” for crimes, allowing officers to stop investigations for lower-level offences where there is little prospect of conviction.