Anglo American, which is developing a major fertiliser mine near Whitby, has confirmed jobs will be lost at the project.
The mining giant will cut the workforce it directly employs at Woodsmith Mine, which will mean a loss of about 180 of the 360 roles.
Contractors have also been instructed to supply fewer staff to the scheme as work on creating one of the two mine shafts has been paused.
Anglo American is looking to reduce spending at the polyhalite mine by more than £2m per day. Work on boring a 23-mile tunnel to the River Tees, where the materials will be processed and exported, will now slow down.