De Beers said on Thursday South Africa’s biggest mining union had said it would declare a dispute in wage talks in which the company is offering up to 7.5 percent in increases.

The National Union of Mineworkers is seeking a 10 percent wage increase, but the company is prepared to offer between 7 and 7.5 percent, De Beers said in a statement.

Under labor law in South Africa declaring a dispute launches a process that includes mandatory mediation before a strike can be called, Reuters reports.

De Beers, the world’s largest diamond producer and 45 percent owned by Anglo American plc, said in a statement that it is “disappointed” with the Union’s response to what the company considers a “generous and progressively structured proposal, but is confident that a settlement will be reached and remains committed to a mutual gains process of negotiation. The parties will meet as soon as possible in an attempt to settle this matter.”

De Beers has over 9,000 workers in South Africa, but the contract covers about 5,400 employees

JCK