Brit holidaymakers warned of little-known passport rule that could see you rejected at the airport gate

• To make sure you can fly, you should always keep your passport in top shape 

British holidaymakers have been warned of a little-known passport rule that could see them turned away at the gate as they are about to board their flight. 

The rule relates to a damaged passport - which could prevent you from flying if authorities are concerned about the validity of your passport. 

If they have concerns over its condition, you may even be held at the airport for further questioning, even if you’ve already landed at your destination. 

While minor scuffs and bent pages on your passport are generally acceptable, you should be extremely careful - always making sure to keep your passport in the best possible condition to avoid being unable to travel. 

With this in mind, it is also a good idea to avoid adding novelty stamps or stickers to your passport as they could delay when you to fly. 

According to the UK Passport Office's website, a passport is considered damaged if 'you cannot read any of your details, any of the pages are ripped, cut or missing, there are holes, cuts or rips in the cover, the cover is coming away or there are stains on the pages, for example ink or water damage'.

One such example occurred when a British holidaymaker was forced to shell out £1,200 for a replacement flight to her dream holiday in Mexico - after being blocked from her original TUI plane over a 'slight mark' on her passport.

Laila March, 25, a private tutor from Croydon in south London, thought she was getting a 'cheap deal' with TUI for less than £1,000 per person when she booked a week's holiday to Cancun with her sister Kaemarnie, 21, to celebrate her graduating from university.

However, after arriving at Gatwick Airport on June 7, Laila was told she could not board the plane because her passport was damaged – even though she uses it to travel regularly for work and had just flown back from Morocco the day before.

They arrived at the North Terminal TUI check-in desk two hours early, expecting to collect their tickets with plenty of time to relax before their flight.

Laila said the check-in assistant scanned their passports and was about to hand over their boarding passes when she spotted a small stain in the top right of her picture page.

'She was like, 'What's happened to your passport? What's this mark on it?',' Laila said. 

'Apparently there was a slight mark on the photo page, but it wasn't over any of the details and you could still read everything.

'She called someone who took my passport and disappeared for half an hour, even though I explained, I flew into this airport yesterday and have travelled many times in the past year.'

After waiting 45 minutes, Laila was informed she could not board the plane.

'They said Mexico has really strict passport control so I might not be let into the country,' said Laila.

'According to them, my passport was damaged so they couldn't allow me to fly with TUI because if I get to Mexico and they send me back, it's going to be a charge for them.'

Laila said she was given three options, to apply for an emergency passport and travel a few days later, to change the name on her booking so someone else could travel in her place, or to see if another airline would accept her passport.

With no time to spare, Laila headed for the South Terminal to plead her case.

In a desperate bid to still travel, Laila decided to try her luck with British Airways, who had 'no issue' with her passport and would happily let her fly. 

Not wanting her sister to travel alone, Laila purchased a last-minute ticket for £1,200 and had no problem clearing customs after arriving in Mexico only a few hours later than expected.

But having to shell out an extra £1,200 put a dent in Laila's savings which she planned on using in September, when she starts her postgraduate degree in education at the University of Cambridge.

She complained in the hope of getting refunded for the pricey ticket and, after initially being told TUI had closed her case, the company agreed to reimburse her.