Regional Development Minister Conor Murphy has rejected calls for his resignation over his handling of a new review of water charges.
The Stormont executive has been discussing rates
The demand was made by Ulster Unionist Fred Cobain who chairs the Stormont Committee shadowing Mr Murphy's department.
However, Sinn Fein has accused Mr Cobain himself of gross incompetence.
The executive has been approving a review of water charges, which is expected to report in the autumn.
However, Mr Cobain is unhappy because he believes his Stormont Committee has been cut out of drawing up the terms of reference for the review.
Mr Cobain has accused Mr Murphy of failing to keep a promise to fully involve his committee in setting the terms for the review.
Set aside £75m
However, Sinn Fein's Raymond McCartney hit back, accusing Mr Cobain of gross incompetence and narrow party politicking.
He claimed Mr Cobain could have given the minister his committee's recommendations last week instead of waiting until Wednesday.
Sources close to the minister have ruled out any resignation over the matter.
First Minister Ian Paisley has said not imposing water charges would save the average Northern Ireland household £100 in the year ahead.
The Northern Ireland Executive has set aside £75m to meet the cost of deferring the charges for the coming 12 months.
However, the Department of Regional Development later said deferring water charges would cost £265m over the next three years.
Meanwhile, the executive has agreed that two ministers will make statements to the assembly on Monday setting out details of reviews on rates and water reforms.
Finance Minister Peter Robinson is to tell the assembly about an accelerated examination of the current rating system with a view to finding more effective ways of insuring a fairer deal for next year's bill.
Conor Murphy will outline the plans for a review of water and sewage.