Solid Energy plans to cut 41 jobs at Stockton opencast mine, which employs 225 Solid Energy staff plus about 44 contractors.
The company announced the plan to workers in Westport yesterday. It said the proposal was part of Solid Energy's on-going response to continuing falls in the international price of hard coking coal.
"This is about a never-ending pressure for the lowest possible cost per tonne we can get to," chief executive Dan Clifford said.
Stockton, like other Solid Energy assets, is for sale. Solid Energy is in voluntary administration.
Mr Clifford said that while a sale would be a great outcome, the latest cuts were about making sustainable changes to the business irrespective of the sale process.
"Whether we were for sale or not, we would be doing this."
It wasn't a "slash and burn exercise", he said.
Closure remained an option for Stockton.
"We have looked at it closely but we believe we have strengthened the financial position by making these changes."
The proposed job cuts would not alter the mine's Monday-to-Friday operation, nor would they alter production, Mr Clifford said.
Solid Energy staff have until March 22 to provide feedback to the proposal. The company will make a final decision at the end of the month.
Stockton mine employed over 1000 people before Solid Energy hit the skids in 2012.