In its latest advisory on what will happen in the event of a no-deal Brexit, the UK Home Office states travellers to Europe will be treated as being from a “third country” under the Schengen Border Code.

The advisory says: “If you plan to travel to the Schengen area after March 29, 2019, to avoid any possibility of your adult British passport not complying with the Schengen Border Code, we suggest you check the issue date and make sure your passport is no older than nine years and six months on the day of travel.”

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According to the Schengen Border Code, third country passports must have at least three months’ validity remaining on the date of intended departure from the Schengen area.

However, because third country nationals can remain in the Schengen area for 90 days (approximately three months), the actual check carried out “could be” that the passport has at least six months validity remaining on the date of arrival.

The advisory adds: “For example, if you’re planning to travel to the Schengen area on March 30, 2019, your passport should have an issue date on or after October 1, 2009.”

The restrictions also apply to five-year child passports. The advisory warns: “If a child’s passport does not meet these criteria, they may be denied entry to any of the Schengen area countries.”

The announcements follow an admission only hours earlier that from the beginning of this month, extra validity will no longer be added to UK passports, making the maximum validity for a new adult UK passport 10 years, or five years for a child.

The advisory says: “We have made this change to follow recommendations set out by the International Civil Aviation Organisation and to help provide clarity about passport validity in the Schengen area in the future.”

New blue passports, replacing the current EU maroon variety, will be issued from “late 2019”, the Home Office said.

A Home Office spokesperson said: “To meet international guidelines relating to maximum passport validity, Her Majesty’s Passport Office no longer carries over any validity from a previous passport.

“This will ensure that people travelling abroad will be compliant with border entry requirements around the world.”

UK travellers will also need at least one of two new European driving permits in the event of a no-deal Brexit, the government further confirmed on Thursday.