The company says it has begun an engagement process with employees
Bord na Móna has confirmed it is to close its briquette factory in Littleton, Co Tipperary where 69 people are employed.
It is to begin a process with employees following a review into its peat briquetting operations.
It says the review was prompted by "the very significant decline" in sales over the past few years.
Increased competition, consumer trends and low oil prices also resulted in a fall in sales.
The review concluded that its Derrinlough factory in Co Offaly, which employs 61 people, will become the sole location for future peat briquette production.
The company’s Littleton facility will continue production until April 2018.
The company says it has now begun an engagement process with unions and employees.
Employees of both briquette factories were briefed on the details of the review earlier.
Speaking after the briefing, head of Bord na Móna Fuels Eddie Scaife said: "This has been a very difficult decision following a period of uncertainty for employees.
"We took a great deal of care with this review to ensure that a wide range of factors were taken into account.
"Briquette sales have declined significantly in the past few years as we have encountered unprecedented market, financial and regulatory challenges."
The Bord na Móna (BNM) Group of Unions says it does not accept the decision to close its peat briquette plant in Littleton.
Its secretary and SIPTU organiser, John Regan, said: "Our members are very disappointed but not surprised by this move by Bord na Móna.
"We do not accept the decision to close the plant in Littleton and it will be opposed by our members by all legitimate means including industrial action.
"There have been issues with sales of peat briquettes in the last two years.
"However, our members believe this move is premature and unwarranted, particularly as the plant is also in a process of diversifying its output with the development of a biomass briquette."