Strike action has affected South Africa focused mine developer DiamondCorp (LON:DCP), it said today.
Workers at the firm's Lace project who are members of the association of mineworkers and construction union (AMCU) went on strike at 6am this morning.
In dispute is management's refusal to employ two full-time shop stewards.
Development tunnelling in the Upper K4 mining block and processing of development kimberlite is continuing with non-AMCU members, the company said.
Chief executive of DiamondCorp Paul Loudon said: "Management is disappointed that AMCU leaders have decided to encourage AMCU members at Lace into industrial action which in the end provides no financial benefits to the mine workforce but is instead self-serving only to the union leadership.
"Management's position is clear: a mine development project of less than 260 workers does not require and cannot afford two full-time shop stewards.
"We feel sorry for the hardship this action will cause for the Lace workers involved and their families."
Further announcements will be made in due course.