A spokesperson for Iarnród Éireann has said its refusal to accept reusable 'keep' cups on some of its train services are for health and safety reasons.
Speaking on RTÉ’s Today with Sean O'Rourke, Jane Cregan said that Iarnród Éireann was not opposed to keep cups, but that they all have very different sizes and there is only a certain capacity under the spout of the catering trolley.
In addition, the closing mechanisms are not all the same on all the cups and if someone was burnt "it would be a very serious problem".
It was not as simple, she said, as "purely using a cup".
Ms Cregan said Iarnród Éireann is currently trialling a dedicated keep cup on its Enterprise services.
She said that people who purchase and use this cup receive a discount on their drinks.
When asked about a claim that a catering assistant filled a keep cup by using a disposable cup and then threw away the disposable cup, Ms Cregan said "this would not be best practice".
However, she said there was a stock control issue with the cups and there was correlation between takings and cups, but this could be changed to counting tea bags and coffee sachets.