Iarnrod Eireann could be losing over 12 million euro a year due to fare evasion.

A survey of over 21 thousand passengers by the National Transport Authority found people were most likely to dodge paying for a ticket on the Dart and commuter services.

The highest fare evasion rate was among those travelling on the commuter trains in Cork at 15 per cent.

Only 11 per cent of under 18s had a ticket - making them the worst age group for fare evasion.