Money Saving Expert founder Martin Lewis has warned people going on holiday this summer over a common mistake people make at foreign ATMs which will cost you a lot of money.

returned on his The Money Show Live on Tuesday, May 20, with a Summer Special all about holidaying this year, including key tips for tourists and how to be financially savvy while going abroad.One of his key warnings centred around foreign cash machines, and how they try to push you to use Pounds rather than the local currency of the country you're in (probably Euros in Europe).

Martin told his ITV1 audience that using a UK card for your spending when overseas is probably better than using the conversion rates provided by local card machines or ATMs when you're on holiday.

Martin warned viewers, even if they're using their normal bank card (ie not a special travel money card) to always pay in the local currency, rather than paying in pounds and having the machine convert it for you.

The reason for this is that the exchange rate (ie the amount of Euros you get for each £1 you spend), even on a non-travel card, is going to be much cheaper on your card than the local cash machine's currency exchange rate will be.

Martin warned: "Most UK cards are still better than the hideous rates you get abroad. Which is why when you go to an overseas ATM and it says 'would you like us to do the conversion for you?' and you go, 'no'. And then it says 'but do you not want us to do the conversion for you?', and you say no and it says 'DO YOU NOT WANT US TO DO THE CONVERSION'.

"The reason they're trying to force you and being so aggressive is that it makes them more money.

"But it doesn't save you money. So ignore their bullying and their threats and their cajoling in order to pay in pounds. You pay in the local currency."

The Martin Lewis Money Show Live from Tuesday, May 20 is still available to watch on ITVX.