Thousands of patients across Europe are being put at unnecessary risk because their pharmacists have given them medicines that have expired or been withdrawn by regulators, a study revealed on Wednesday.

Based on an analysis of 250,000 prescriptions filled this summer across Belgium and Greece, academics working with Aegate, a drugs safety company, found that almost 1 per cent of drugs requested had been recalled by regulators and should not have been on sale by pharmacists but returned to the manufacturers. A further 0.04 per cent were being offered for sale although they had already passed their expiry dates and were also no longer approved for use by regulators.