TORONTO, April 1 (Reuters) - Dominion Diamond Corp said on Monday that it had secured all necessary regulatory approvals to acquire BHP Billiton's Ekati diamond operations in Canada's Northwest Territories.

Toronto-based Dominion Diamond, formerly known as Harry Winston Diamond Corp, said it expected the deal to close on or about April 10.

Anglo-Australian mining company BHP Billiton agreed to sell its Ekati diamond operation in Canada's far north to Harry Winston for $500 million last November.

In a separate deal in January, Harry Winston said it would sell its high-end jewelry arm to Swiss watch maker and retailer Swatch. As part of that deal, Harry Winston would rename itself Dominion Diamond Corp.

On Monday, Dominion said Canada and Northwest Territories had confirmed that it would receive regulatory approvals needed to complete the acquisition of BHP's stake in the Ekati diamond mine as well as associated diamond sorting and sales facilities in Yellowknife, Canada, and Antwerp, Belgium.