“We apologise for the mistake made by our rental agent at Marseilles and are investigating this miscommunication as a matter of high priority.

“The erroneous charge is due to a system error on some prepaid reservations that we are working to correct.

“However, the location amended the rate for this customer, and no additional charges were applied to his card.”

UPDATE: Avis issued an updated statement on Friday afternoon, making clear that the Brexit tax remark was an "insensitive joke".

The Avis spokesman said: "In light of the recent media attention regarding the incorrectly processed charge resulting from an exchange rate issue added to the car rental of a British customer in France, we wish to strongly express the fact that Avis as an organisation has no view on Brexit. Avis is a global company serving global customers. We are committed as an organisation to serving all our customers to the highest possible standards.

"This unfortunate incident at Marseille was a result of an insensitive joke made by one of our rental staff to a customer over an additional charge, subsequently refunded on the spot, based on a slight exchange rate difference.

"We are working with our rental and customer service teams globally to ensure that the company is not misrepresented in this way, and that our customers feel respected and valued."