Phoenix Natural Gas was criticised today after announcing it was putting up the price of gas in the North by almost 11 per cent from tomorrow.
The General Consumer Council expressed its disapproval at what it called the "excessive" 10.8 per cent rise.
With one-in-three gas consumers in Northern Ireland living on less than £135 sterling a week, the council said it was particularly concerned about the impact of the rise on people who were already finding it hard to make ends meet.
Chairman Mr Steve Costello said: "Consumers will find it hard to understand the sheer size of this increase after three years of relative price stability.
"The price increase will add to the plight of many households who cannot afford to keep warm this winter."
He pointed out Northern Ireland had the highest level of fuel poverty of any region in Britain and said it was ironic the announcement came at a time when many organisations - including the British government - were working hard to eliminate fuel poverty.
Sinn Féin's Equality and Economy spokesman, Dr Dara O'Hagan, expressed sharp criticism of a price rise which she said could push thousands of families in fuel poverty.
Dr O'Hagan said the rise would have "potentially serious consequences".
PA