Bord Gáis Energy has announced increases to average electricity bills by 27% and to average gas bills by 39%, effective from April 15.
Managing director Dave Kirwan said the tariff hikes are due to continued increases in wholesale energy costs over the past two years, particularly in the past 12 months.
"The range of factors driving the rising cost of wholesale energy have been extensively discussed in recent times," he stated. "These include the persistence of high demand on gas worldwide, reduced supplies, low storage volumes, geo-political issues and late winter conditions.
"This, together with the expectation that costs will remain both high and volatile for some time, means we are forced to increase our prices," Kirwan added.
"We know that each customer’s circumstances are different, and we are determined to help those who need it most. That is why we are announcing an energy support fund of €1.25m in addition to the services we already have in place."
The energy supplier said that it expects that some customers will experience difficulties in managing their bills and is working in partnership with the Money Advice and Budgeting Service and other charities.
Other utility suppliers are expected to raise their prices in the coming weeks.