Manufacturers in Northern Ireland said they support the Utility Regulator in a row with NIE over the cost of investment.
NIE, owned by the Irish state-owned Electricity Supply Board (ESB), has asked the Regulator to approve over £600m in investment over the next five years. But the regulator will only sanction investment spending of £293m.
Bryan Gray, chief executive of Manufacturing Northern Ireland, said: "Competitive electricity costs are vital for the recovery of the manufacturing sector from the present recession.
"Commercial consumers here are already paying some 60% more than their counterparts in the Republic of Ireland for this element of the electricity bill.
"NIE's proposals will make that situation even worse with a significant impact on jobs and prosperity in Northern Ireland.
"In view of the fact NIE's owners ESB, who are a state owned company in the Republic, may be privatised in the near future, questions need to be asked about the motivation for NIE's proposed major investments at this time."