Holidaymakers should steer clear of foreign exchange bureaus at Luton, Newcastle and Liverpool airports, which provide the least competitive currency conversion rates.

Changing money at Leeds and Bradford airport could also be an expensive mistake, according to research into the costs of exchanging money at UK airports by FairFX, the foreign currency specialist.

Airports are one of the most expensive places to buy currency. It costs an average £6,434 to buy €7,500 at a UK airport currency exchange, the research found.

Some airports are worse than others because commision rates vary.

Buying the same amount of Euros at an ICE bureau de change at Luton airport would have set you back £6,608, for example. This includes a commission of £4.50. If instead you bought from an ICE bureau at Gatwick, one of the most competitive airports, you would be charged only £6,257 – a saving of £351. Other competitive airports, if you convert currency at the last minute, include Gatwick and Heathrow.

Stephen Heath, chief executive of FairFX said: "Most providers rely on the fact holidaymakers will be in a complete rush when preparing for a trip abroad, and fail to organise currency before they get to the airport.”

Other methods of converting currency tend to be cheaper. The same €7,500 would cost £6,136 if you took it out using a debit card and £6,181 if you ordered the currency from a specialist online foreign exchange broker.

Pre-paid cards, where you load money onto a foreign currency card, offer some of the best exchange rates and charge around £6,011 for the above sum. They work just like a debit cards but can be topped up via the internet or by text.

If you use your debit card abroad, you will usually be hit by a cash-conversion charge of about 2.75 per cent as well as a transaction charge of 1.5 per cent to 2 per cent, if you use a foreign cash machine. You will face similar charges on purchases.

Debit card fees are on the rise. From next month Alliance and Leicester card holders will see their foreign usage conversion charge increased by 0.20 points to 2.95 per cent. Its foreign usage cash transaction charge will be increased from 1.5 per cent to 2 per cent, with a minimum fee of £2.

Using credit cards for cash withdrawals is also expensive. Not only will you be charged a higher rate of interest from the date of withdrawal, you will also pay a cash handling charge.

There are some advantages tousing a credit card for purchases abroad however. The Consumer Credit Act gives you the same protection overseas as you receive in the UK if goods prove to be faulty. It means you can claim your money back from the credit card firm as long as the goods cost between £100 and £25,000.

Nationwide building society does not charge fees on its debit or credit cards making it one of the cheapest ways to take out money abroad.