Travellers are reported to be offered less than €1 to the pound after the value of sterling sank to its lowest level since Britain voted to leave the EU.

Bureaux de change at two UK airports are offering 99 cents for £1, according to the foreign currency specialist Caxton FX.

Moneycorp at Stansted is offering €0.9915, while the rate from International Currency Exchange (ICE) at Luton airport is €0.990,

The rates are significantly below the market exchange rate, which was €1.15 last night, reflecting the huge mark up that airport operators charge tourists, The Times reported.

However, experts also accused the companies of taking advantage of the falling pound since the Brexit vote to increase their profit margins.

In mid-April, ICE was offering 10% less than the market rate but the rate at Luton this week was 14% lower, according to FairFX, an online bureau de change.

Guy Anker, of the consumer website, said: “Airports have always been the worst place to buy currency but the bureau de change rip-off has got even worse since the Brexit vote.

“Holidaymakers will have heard that sterling has fallen without knowing to what rate and airport operators are exploiting that.”

The pound hit its lowest level in three years against the euro on Monday, meaning Britons are suffering at the peak of the summer holiday season when millions travel abroad.

Parity between the euro and sterling means a beer in Paris will cost £5.85 and entry to the Colosseum in Rome is £12.

The pound has now fallen more than 12% against the euro and 10% against the US dollar since the referendum on June 23. On the night of the vote £1 was worth €1.31.

The exchange rate recovered slightly on Tuesday following news that inflation had hit 0.6%.

Holidaymakers can get better foreign exchange deals online or on the high street than at airports. Yesterday was offering €1.1258 per pound to customers who changed more than £500.

Withdrawing money from foreign cash machines is also cheaper.

ICE told the newspaper that it generally did not charge commission online but did in airports because of the “higher operating costs”. Moneycorp said that it had not increased its margins and that rates online differed from airport rates.

Tracy Bownes, retail director at moneycorp said: “The reason for our higher airport rates is the significant cost associated with operating there – from ground rent and additional security, to the cost of staffing the bureaux for customers on early and late flights.

“An easy and more cost-effective way for customers to buy travel money is to pre-order online and collect at the airport.

“We always encourage our customers to do this, and increasing numbers of people are planning ahead in this way – we’re seeing up to 50% of transactions coming from reserve and collect customers at some of our airport bureaux.

“Our online reserve and collect rates are always highly competitive, and are often cheaper than specialist travel money cards available in the UK.”

She added: “It’s important for customers to be aware that they should look at fee as well as rate when they are purchasing travel money. Many operators include a commission fee which is often carefully hidden in the small print. Moneycorp charges 0% commission on all currency orders.”