OZ Minerals expects to take a hit of up to $240 million due, in part, to lower copper and gold prices and a landslip at one of its mines.

The company expects its six monthly earnings results, due next month, to show a non-cash asset impairment charge of between $200 million to $240 million after tax.

In a statement on Monday, the company said the impairment charge was due to a combination of factors including: lower than expected copper and gold prices, development work and a landslip at its Malu mine in South Australia.

OZ Minerals will release its half yearly earnings results on August 14.

The company last week cut its production guidance for 2013 to between 120,000 ounces to 130,000 ounces of gold, from the previous range of 130,000 to 150,000 ounces, as a result of the landslip.

Shares in OZ Minerals dropped more than seven per cent last Thursday, after the lower production guidance was announced.