Aug 30 (Reuters) - Bluescope Steel Ltd BSL.AX
* Proceedings have been issued in New Zealand against one of its subsidiaries, Toward Industries by Nz Iron Sands Holdings
* Bluescope and toward consider NZIS claims to be completely unfounded
* Proceedings relate to NZIS' failed attempt to buy Toward's Taharoa Iron Sands mining business
* NZIS is claiming loss of opportunity for NZSM to make trading profits that NZIS calculates as $886m for period 2017 to 2029