A slate firm in Gwynedd, at the centre of an internal financial inquiry, is to lay off 38 temporary workers.
McAlpine's Penrhyn quarry in Bethesda
The Penrhyn quarry slate subsidiary of Alfred McAlpine plc earlier this week revealed it had suspended two managers as part of the company's investigation.
It said "accounting irregularities" had been uncovered worth up to £24m.
Unions said after a meeting that it had been "impossible" for management in Bethesda to give assurances that there would not be future job losses.
In a statement the company said: "During the meeting the difficulties being experienced at Penrhyn were shared with the unions and management undertook to consult the union going forward".
The statement added that 38 temporary employees would be "released either this week or next. All are employed at the Penrhyn quarry."
The company employs around 450 people in north Wales and north America - the majority working in north Wales.
Paddy McNaught, of the T+G union, said: "We have given assurances that we will work with the company to protect the future of the slate industry in this region.
"At this moment in time it is impossible for the company to give us assurances that there won't be any further job losses as a result of the current review of slate production in north Wales."