Gas prices are to be cut by more than 14%, Phoenix Gas has announced.
NI prices remain higher than British prices
The decrease comes just a few months after it raised prices for the third time in one year. Last September, the company increased the tariff by 14.5%.
Phoenix put up its prices in January 2006 by 17% and that came after a 30% hike in September 2005, prompting outrage from the Consumer Council.
A 14.6% reduction, effective from 31 March, resulted from the fall in the wholesale cost of gas over the winter.
It means the average domestic bill would fall by £89 a year - £1.71 per week.
Peter Dixon of Phoenix said: "I would hope the news today marks the beginning of a period of price reductions and as part of our commitment Phoenix will be carrying out a further review of prices by the end of this summer."
He said the company had consulted with the Northern Ireland Authority for Energy Regulation, the Consumer Council and the Department for Enterprise, Trade & Investment.
The Consumer Council has said it hopes Phoenix will be able to make further price cuts in the future.
Joanne Gamble, head of energy at the council, said she wanted to see customers in Northern Ireland paying similar prices to those in the rest of the United Kingdom.
"There are some legitimate reasons for that because gas is a new industry for Northern Ireland and we have to bring the gas across in the pipeline," she said.
"However, we calculate that the difference is running at about 30% and that, in our view, is too high.
"Hopefully, when prices are reviewed again we will see a further drop and a closer convergence."
Ofreg has welcomed the reduction "as reflecting appropriately recent reductions in wholesale gas costs".
Chief Executive Iain Osborne said it was "clearly welcome for gas consumers, who have often struggled to afford previous tariff increases".
"NI prices remain higher than British prices. There are many reasons for this differential including the method and stage of development, size of market and interconnector costs," he said.
"We would of course hope that this is the beginning of at least stable, if not falling, prices and renewed confidence in the Belfast gas market.
"We continue to monitor gas costs and will review tariffs again in October to see if further reductions are possible."