The board of directors of Bord na Móna is expected to approve a plan tomorrow that will lead to the loss of 150 jobs before Easter 2019 and up to 850 redundancies in the peat harvesting business by 2025.
The move is part of the company's restructuring as it moves to decarbonisation of the fuel sector in the next ten years, before stopping all sales to the ESB in 2030 or before that.
It is ten years since Bord na Móna committed to stop harvesting peat in new bogs under "A New Contract with Nature".
Three years ago, as the calls for decarbonisation continued, the company announced it would exit all peat for energy purposes by 2030.
In effect, this means peat sales will reduce from a million tonnes per year to just 350,000 tonnes in a very short period of time, meaning job losses are inevitable.
After company directors sign-off on a new strategy tomorrow, 150 jobs will be lost before next Easter, some voluntarily.
Another 250 people, including middle management and administration staff, are expected to leave in the following 18 months. There will be 850 fewer workers employed by the company by 2025.
Offaly County Council called on the board to move swiftly to a new up-skilling plan for retiring staff.
Sinn Féin's jobs spokesperson and a Fine Gael MEP have also both called for supports for workers who face job losses.
Maurice Quinlivan, Sinn Féin TD for Limerick City, called on the Government and enterprise agencies to direct resources into sourcing jobs for the area affected.
Ireland South MEP Sean Kelly has called on the Government to ensure that money raised from the auctioning of carbon allowances under the EU's emissions trading scheme is allocated to supporting the workers and areas affected.
Earlier, Fianna Fáil TD Barry Cowen said he was expecting the company to announce up to 300 job losses to be announced tomorrow as peat production ceases in 17 bogs.
The Offaly-North Tipperary TD is calling for a sustainable transition forum for the midlands as the company moves away from peat harvesting.
A spokesman for Bord na Móna said the company would not be making any statement ahead of a board meeting tomorrow.
It is anticipated the job losses will occur in counties Kildare and Offaly.
"The Government cannot just leave this region and in particular these communities on its own after such an announcement," said Mr Cowen.
He said: "I have personally written to An Taoiseach requesting his support in the establishment of such a forum. The Government cannot wash their hands of this devastating blow; they must support the workers and the local economy."
The ESB's failure to yet lodge planning applications to convert Shannonbridge power station in Co Offaly, and Lough Ree power station in Co Longford into co-firing biomass and peat plants is also leading to concerns about the future of the plants.
Although the application is expected next month, it is likely to be opposed on environmental grounds and face consequent delays. Concern also remains about the sourcing of adequate quantities of biomass to co-fire the plants.
Mr Cowen said he has also written to EU Commissioner, Margrethe Vestager, and other commissioners, seeking a meeting at their earliest convenience to discuss how the EU fund can support workers, their families and contribute towards enterprise and innovation funds in the affected regions.