Alcoa saw its shares fall 6.5 per cent on Wednesday after the US metals group said it would be unable to fulfil its alumina supply contracts and downgraded its second-quarter earnings estimates.

This is one of the consequences of last week’s explosion at a gas processing plant in Western Australia. Several other mining companies in the state, one of the world’s most important minerals-producing regions, are also cutting targets for this year following the accident, which has reduced local gas supplies 30 per cent.