The passport check service falsely told thousands of parents their children's passports were invalid.

Families who were due to depart on holiday were sent into panic mode when the Government website told them they would not be accepted into European Union countries with their passports.

Travel expert Simon Calder described the aftermath of this mistake as "carnage" for travellers.

"It was extraordinary at the weekend," he told Sky News.

"The numbers weren't huge travelling but they're still bigger than they had been all through the year, and around about lunchtime on Saturday I had parents contacting me on social media saying, 'Help our kids' passports are no longer valid for travel in Europe." 

Mr Calder said when he checked the date of issue for these passports, he found all documents were still valid as per the Government's most recent advice for foreign travel after Brexit.

"Since Brexit it's got a lot more complicated in terms of passport validity," he explained.

"The general rule is that your passport must be valid for at least three months after you intend to come back.

"The Government's passport checker system - I've already been talking to them since the start of the year about how deeply flawed it is for adult passports.

"It was then just randomly telling parents that they their kids passports weren't valid there were people booking flights to Belfast from London because it's the only place they could get a fast track appointment.

"[It was] absolute carnage."

On Sunday, the passport checker was "taken down" from the Government website.

A Home Office spokesperson commented: "The passport checker is intended as a guide to help customers decide whether they need to renew their passport for travel to Europe.

"We are aware of an issue with the advice when checking some children's passports, and so have taken the checker down while we investigate.

"You can continue to find information about the new rules on gov.uk.

"It is for carriers to determine that they are satisfied their customer's travel document meets the entry requirements of the country that they are travelling to."

Now when holidaymakers search for the webpage they are greeted with a warning message stating: "Sorry, this service is unavailable. You'll be able to use the service later."

In the meantime, Mr Calder urges Britons to "check your passport expiry date."

"I hope when they come back with a new version, it actually bears some resemblance to reality in the shape of what Europe's passport rules actually are."

The Government website holds information regarding passport validity since the UK left the EU.

"You need to have at least six months left on an adult or child passport to travel to most countries in Europe (not including Ireland)," states the Government travel advice.

"If you renewed your current passport before the previous one expired, extra months may have been added to its expiry date. Any extra months on your passport over 10 years may not count towards the six months needed."