Posco of South Korea, the world's fourth-largest steelmaker, has moved to strengthen the security of its coal supplies by joining ArcelorMittal and China's Citic on the share register of Macarthur Coal. The three groups together now control almost half of the A$4.2bn (US$4bn) Australian group, making it virtually impossible for one of them to launch a successful takeover bid for Macarthur without the others' agreement.

Alcoa saw its shares fall 6.3 per cent yesterday 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 far-reaching consequences of last week's explosion at a key 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 by 30 per cent.