About 2,000 workers at LafargeHolcim'sSouth African unit will on Thursday launch an open-ended strike over pay, a labour union said on Wednesday.

"The industrial strike would encompass the entire workforce and it will be a total withdrawal of labour by our members working at LafargeHolcim," the National Union of Mineworkers (NUM) said in statement.

LafargeHolcim spokeswoman Unathi Batyashe-Fillis did not immediately respond to a request for comment.

The NUM is demanding a pay increase of 13 percent, more than two times the official inflation rate.

Wage settlements in South Africa, which have averaged about double the inflation rate in recent years, drive up the cost of labour in an economy that has hardly grown since emerging out recession in 2009.