The policy, which was not publicly known until it was reported in Le Parisien, has sparked fears that conductors are being incentivised to issue frivolous fines for their personal benefit.

The internal SNCF document also shows that conductors receive a smaller commission if fines are not paid on the spot.

“That’s why some conductors are so insistent,” a chief conductor told Le Parisien. The commission can drop to “less than €1” in that event.

However, he added: “More often than not, most of us are understanding. One shouldn’t generalise.”