French Customs Officers in Avignon are dipping yacht tanks to see if they are burning red diesel and if so are imposing fines.

They are claiming that this is against French law. Proof that the diesel was purchased outside France is of no interest to them.

An RYA spokesman said: ‘We believe this to be in contravention of EU law and are taking the appropriate action – in the mean time however, you are advised to ensure that you use as much red diesel as possible before re-filling with white diesel to ensure that traces of red diesel are kept to the absolute minimum and to keep your receipts.’