Atlas Iron will record a non-cash impairment of up to $100 million in its full-year results after rising costs led to an operating loss in its third quarter.

The iron ore miner says it will make an impairment of between $75 million and $100 million, but warns the final figure will not be known until it audits its books for reporting to market in August.

Atlas Iron says it has been adversely affected by discounts applied to lower-grade iron ore and rising sea freight and fuel prices, although any impairment for the 12 months to June 30 reporting period will have no impact on cash flow or its debt obligations.