South Africa's National Union of Mineworkers (NUM) on Friday declared war on De Beers, accusing the world's top diamond producer of reneging on a deal for a wage increase.

The union on Thursday announced that De Beers had agreed in principle to a 12 percent wage rise for its members but said the diamond producer then proposed a different deal.

The union said it was now demanding a 13.5 percent wage increment and would not go back to the earlier 12 percent deal it said in a statement De Beers had reneged on.

It added that De Beers negotiators had earlier agreed to the 12 percent wage increase, and then put forward a different draft that spoke a different language.

We are folding our sleeves for a big fight. De Beers will never be allowed to successfully lie to workers. We will take the fight to them, said Peter Bailey, the union's chief negotiator. It is either 13.5 percent or it is war.

De Beers, which is 45 percent owned by global miner Anglo American , said the union released news of an agreement that had not yet been finalised.

The NUM put out an announcement of an agreement that was not really in place and they have since retracted it, De Beers spokesman in Johannesburg, Tom Tweedy said.

The union also declared a dispute with the country's arbitration authority, a required step before the union can legally call a strike.

Under South African law, the arbitrator brokers future negotiations to help spur a settlement but if the two sides cannot agree then the union can legally move to strike.

Workers are increasingly demanding double-digit increases as South Africa's inflation soars. The country's annual CPIX inflation hit a fresh 5-1/2 year high in May, at 10.9 percent. (Reporting by James Macharia; Editing by Michael Kahn)

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