Workers at Bord Na Móna are taking part in two days of strike action in a dispute over pay at the company.
Harvesting activities have been suspended in Longford, Westmeath, Laois, Offaly, Kildare and Roscommon, where 1,500 workers are back on the picket lines for the second time in less than a month.
Pickets have also been placed at briquette factories in Offaly and Tipperary and at a supply depot at Edenderry power station in Co Offaly.
The company offered to pay 3.5% extra in two phases and a lump sum of €1,000 to every worker.
However, the group of unions still wants all increases to be made pensionable and no progress has been made between the sides.
Briquette production will be worst affected by the action.
ESB power stations will not be disrupted, but the timing of the action is critical as the company's peat harvesting targets are already well in arrears after bad weather.
The human resources director at Bord na Móna said the company is making significant losses during the industrial action.
Jim Stockwell said the company had negotiated a fair deal with unions representing the workers last April, which was accepted.
Secretary of the Bord na Móna group of unions Oliver McDonagh said the unions are available to meet a third party to try to resolve the strike.
He denied that the future of the company was being put at risk because peat harvesting levels were already low.
Mr McDonagh said Bord na Móna had good years and bad years in the past and had made significant profits during the good years.
