Diamond producer De Beers said on Friday it had signed a new 10-year contract for the sorting, vaulting and sales of the diamond production of Debswana, its joint venture with the government of Botswana.

De Beers, 45 percent-owned by global miner Anglo American, said in a statement it is the longest sales contract to date between the partners. Debswana is the group's major producer.

As part of the deal, De Beers said it would transfer its London-based rough diamond sales operations to the southern African nation by the end of 2013.

Botswana is the world's largest supplier of diamonds and the agreement maintains De Beers' access to the country. De Beers, founded in the late 19th century, controls around 40 percent of the global rough diamond market.

Sparsely populated Botswana is keen to diversify its economy by moving into the sales side of the diamond industry.

Diamonds De Beers London Anglo american plc