Coal prices in Northern Ireland are set to rise by as much as 10%.
The Coal Advisory Service said the major importers of the fuel had informed it the increases are imminent.
Economy coals will increase by around 10% while bituminous coal will rise by between 4% and 6%, smokeless coal prices will go up by between 7% and 9% while manufactured ovoids will increase by between 5% and 6%.
The service stressed that the rises, blamed on increasing cost pressures in the world market, were significantly lower than hikes to other energy sources.
The prices are likely to increase from early to mid September.
The Consumer Council said the announcement is was a further blow for customers who are struggling with their energy costs.
John French, head of energy at the Consumer Council said: "In light of the recent increases in electricity prices and now coal prices, we call on the Northern Ireland Executive to address urgently the issue of energy affordability in Northern Ireland before living in a warm and dry home becomes simply unaffordable."
The council said that while only around 5% of households in Northern Ireland use coal to solely heat their homes, there is an increasing number that use coal fires as a means of complementing their central heating systems.