Border Force staff check passports of motorists arriving at the U.K. border | Matt Cardy/Getty Images European Commission publishes briefing on no-deal Brexit planning The paper urges private companies and individuals to ‘take responsibility for their individual situation.’

LONDON — Transport between the EU and the U.K. will be “severely impacted” with roads and ports blocked by customs queues and millions of British and EU citizens would be left in legal limbo if the U.K. leaves without a deal next March, the European Commission said Thursday in a briefing on Brexit preparations.

The document, aimed at EU member countries, the European Parliament and other EU institutions, says that preparing for all Brexit scenarios is “a matter for everyone” and urges private companies and individuals to “take responsibility for their individual situation.”

Fears of a no-deal “cliff-edge” Brexit have increased in recent weeks after a new Brexit plan unveiled by U.K. Prime Minister Theresa May last week prompted the resignation of her Brexit secretary and foreign secretary, with Brexiteer MPs signaling they would block a deal on May’s current terms.

While the EU is “working hard to reach an agreement on an orderly withdrawal,” according to the new document, published on the same day new Brexit Secretary Dominic Raab holds his first meeting with EU chief negotiator Michel Barnier, “there is no certainty that an agreement will be reached.”

With no agreement by March 2019, or if an agreement is not ratified by the U.K. and European parliaments and the European Council by this date, “there will be no transition period and the EU law will cease to apply in the United Kingdom as of 30 March, 2019,” the document states.

The document emphasizes the role of member countries, regional authorities and businesses “of all sizes.”

Such a scenario would mean “no specific arrangement in place for EU citizens in the United Kingdom, or for U.K. citizens in the European Union.” Additionally, the EU would apply third-country checks on all U.K. goods entering the EU “for customs, sanitary and phytosanitary standards and verification of compliance with EU norms,” the document says.

“Transport between the United Kingdom and the European Union would be severely impacted,” it adds. "Controls at borders could cause significant delays, e.g. in road transport, and difficulties for ports.”

While outlining legal preparations within the EU, the document emphasizes the role of member countries, regional authorities and businesses “of all sizes” assessing the impact of no deal on their own activity.

“Although the withdrawal of the United Kingdom may appear to be playing out at a high and rather abstract level between the United Kingdom and the European Union, its consequences will be very real for citizens, professionals and business operators,” the document says.

However, it proposes that even in a no-deal scenario, the U.K. and EU may quickly recommence negotiations to establish a new legal relationship. “Depending on the circumstances leading to the withdrawal without an agreement,” the document states, “the EU may wish to enter into negotiations with the United Kingdom as a third country.”