JOHANNESBURG (Reuters) - The world's top diamond producer, De Beers, said on Thursday it was continuing wage talks with South Africa's largest mineworkers' union in a bid to avert a strike at its mines in the country.

"We don't have an agreement signed, but we're optimistic that we have an attractive offer on the table," De Beers spokesman Tom Tweedy said. "We're optimistic we'll find a settlement."

A spokesman for the National Union of Mineworkers (NUM), which represents 3,400 workers at De Beers, was not immediately available for comment.

The union had announced a one-day strike beginning Thursday evening to press its demands for a 13.5 percent wage increase.

De Beers, which is 45 percent owned by mining group Anglo American, has offered 11 percent over two years.

The union called for the strike after an arbitration authority failed to successfully mediate the wage dispute.

Miners in South Africa have been demanding double-digit wage increases to soften the blow of rising fuel, food and electricity prices and a string of interest rate hikes that have made house and car loans more expensive.

South Africa's inflation rate is hovering around 11 percent.

Workers across the country have started a series of rolling strikes to protest the cost of living. The powerful Congress of South African Trade Unions is spurring the protests, which will culminate in a national strike next month.