Which? says additional entry checks at some of Europe’s most popular holiday destinations could result in significant hold-ups for travellers.

According to Which?, Alicante would be worst affected if Britain leaves the EU without a deal, with 43% of all its passengers arriving from the UK.

The watchdog’s analysis estimates a no-deal scenario would result in an additional 201 hours of immigration checks, on average, every day.

Moreover, Spain would likely be the destination hardest hit by no-deal, home to six of the top 10 busiest airports for UK arrivals.

Besides Alicante, these include Tenerife South, Lanzarote, Malaga, Ibiza and Palma de Majorca.

Which? says these airports face “severe difficulties” if no contingent arrangements are made to service the additional entry checks.

Checks include passport validity and expiry dates, visitors’ purpose and length of stay, and whether they’re able to financially support themselves.

The European Tourism Association (Etoa) estimates the additional checks required in the event of a no-deal Brexit could add an extra 90 seconds at border control for each UK passport holder.

This translates to more than four-and-a-half hours’ additional checks per typical Ryanair flight, an issue Which? says is further exacerbated by the rate of arrivals from the UK, with Alicante currently welcoming as many as 10 flights from the UK in a single hour.

Rory Boland, Which? travel editor, said: “Airports can be chaotic at the best of times, but if additional checks at passport control in Spain, Italy and other popular EU destinations are implemented in the event of a no-deal, it seems that very long queues are going to be an unwanted side effect.

“Until there is a deal or these airports announce simpler arrangements, you should consider what you may need if you have to fly to them – as it is very likely that you’ll be in a queue for several hours. Make sure you have food, water and essentials for kids like nappies to hand.”