Update 3.20pm: The Transport Minister says he has not been told of possible rail strikes on Christmas Eve, but hopes they will not happen.
Workers at Irish Rail have announced details of five strike days over pay, with the second due next Tuesday.
They are looking for pay hikes of 11% over three years which Irish Rail says they cannot afford.
Minister Shane Ross says he hopes the strike won’t escalate.
He said: "I sincerely hope that won't happen, I read reports of it in the newspaper this morning and I urge the party's management and unions to go back to the WRC and Labour Court as soon as possible.
"I will not be intervening."
Earlier: Train services return this morning following industrial reaction
Trains are running as normal across the country this morning after yesterday's 24-hour strike.
More than 150,000 passengers faced travel disruption because of a pay dispute between management and workers at Irish Rail.
Transport Minister Shane Ross is being urged to intervene before another four days of planned industrial action kick in.
Siptu's Greg Ennis said his members are resolute.
"They are strong, the picket lines have got a lot of support from members of the public. The workers in this country are starting to stand up and say 'Do you know what? If politicians can get a pay increase then so can we'," he said.
"It's about time that Irish Rail workers got a pay increase which is in line with what happens in the transport sector," Mr Ennis added.