The Consumers Association of Ireland has criticised the latest increase in gas prices, which comes into effect today.
Prices for domestic customers have been increased by 10.9%, while businesses are facing a 16% increase.
Bórd Gáis has defended the hike, saying domestic gas prices in Ireland were 21% below the EU average.
However, Michael Kilcoyne of the Consumers Association said it was completely unwarranted.
"The increase that's being applied from today is five times the rate of inflation," he said.
"We do not believe that there is any justification whatsoever for this scale of an increase and we are extremely disappointed that the regulator has approved it."