BHP Billiton has signed an agreement with Leighton Holdings to acquire HWE Mining subsidiaries for $735m.

HWE Mining subsidiaries provide contract mining services to BHP’s Western Australia iron ore operations.

Under the terms of the agreement, BHP will acquire the mining equipment, people and related assets that service Area C, Yandi and Orebody 23/25 operations, which account for 70% of Western Australia Iron Ore’s total material movement.

The acquisition is part of BHP Billiton’s plan to move the Western Australia iron ore business from contract mining to owner-operator mining.

The transaction is expected to close in the fourth quarter of 2011.