Business travellers have been warned they could be turned away at EU borders after a no-deal Brexit.

Consultancy EY said they may have to obtain work permits which could take months to secure if immigration rules are enforced.

Seema Farazi, head of financial services immigration, told the Financial Times: “As of November 1, assuming a no-deal exit on October 31, businesses will have to navigate red lines across each of the EU27.  This is a sea change for UK businesses, used to the flexibility that has come with free movement.”

Prime minister Boris Johnson has promised Britain will leave the EU by October 31, with or without a deal.

If it leaves without a deal, British citizens will have to apply for work permits on a country-by-country basis if they do more than attend business meetings, networking events or conferences.

The CBI business lobby group warned of “immediate overnight disruption” for UK businesses that sent staff to the EU for work and said companies may eventually relocate operations and jobs to the EU as a result.

Germany is one of a number of countries which has prepared waivers for UK workers on stays of up to three months, but others have stricter rules.