The car hire company has been accused of over-billing “half a million” customers for repairs, according to reports in The Telegraph.

In light of The Telegraph’s investigation, the Serious Fraud Office is preparing a criminal inquiry into Europcar, probing potential “fraudulent charges for windscreens and other repairs”.

Consumer watchdog Which? is also calling for a wider inquiry from the government to establish if other car hire firms could be profiting from similar illegal tactics.

Alex Neill, managing director of home products and services at Which?, told The Telegraph that consumers will be “outraged” if Europcar is found to have inflated costs for repairs.

Neill said: “There should be an immediate investigation to ensure others aren’t doing this and customers who have been left out of pocket are compensated without delay."

Europcar currently operates in 140 countries worldwide, with a revenue of nearly €1.75 billion euros per year.

In a statement, Europcar said it had launched its own investigation and added: “Europcar’s view is that the implications of the investigation will be somewhere in the region of £30 million.”

However, once the inquiry is finished, the figure could be considerably higher.