Micheál Martin suggests that "only Government can bring in a money bill, not opposition"
Fianna Fáil says it will not support a Sinn Féin motion in the Dáil next week to scrap water charges - despite it being party policy.
The party's leader Micheál Martin has accused Sinn Féin of "play acting" with a motion when the Dáil returns next week, as only legislation can end the charges.
Charges are currently suspended for a period of nine months, while an expert commission is examining the future of public water services.
Speaking as his party gathered in Carlow for a parliamentary party 'think-in', Mr Martin says the motion has no legal standing.
"The only way you can get a rid of charges is by a money bill, in other words legislation - [and] only Government can bring in a money bill, not opposition" he explained.
"We've brought about the ending of the water charges regime. It's far more effective politics than that practiced by Sinn Féin and others, because executive action isn't about motions," he added.
Earlier, Fianna Fáil TD Thomas Byrne suggested that "water charges are gone and I don't believe they're coming back".
Sinn Féin, meanwhile, has called on Fianna Fáil to support their motion.
The party's MEP Lynn Boylan said: “The Dáil can vote in favour of abolition as early as next week and, in doing so, deliver what people actually voted for at the General Election in February. They didn't vote for a suspension of water charges. People want to see them scrapped.
“The Sinn Féin motion is extremely clear and direct in its purpose. Failure by Fianna Fail to support this motion would cement the view that they cannot be trusted on water charges," she argued.
On Saturday, tens of thousands took part in a national demonstration in Dublin city calling for water charges to be abolished.