After weeks of dilly dallying and speculative talks, global miner BHP Billiton has finally dropped the bomb and confirmed it is dropping all plans on the supposed $30-billion expansion of the Olympic Dam copper and uranium mine mega project in South Australia.

This as the company on Wednesday reported its full-year profit to the end of June dropped 35 per cent to $17.1 billion from $21.7 billion a year ago, its first drop in annual profit for three years, on rising costs and falling commodity prices.

The development of a Queensland coal deposit has likewise been deferred.

"As we finalised all the details of the project in the context of current market conditions, our strategy and capital management priorities, it became clear that the right decision for the company and its shareholders was to continue studies to develop a less capital intensive option to replace the underground mine at Olympic Dam," BHP Billiton CEO Marius Kloppers said in a statement.

The Melbourne-based Anglo-Australian giant said it would revise and work on a cheaper design on the expansion of the Olympic Dam open-mine pit expansion. It would also not approve any expansion on or before December 15, the date its indenture agreement reaches deadline with the South Australian government.

No definite timeline was mentioned on the announced revised expansion.

The mining giant likewise announced a dividend of 57 US cents, fully franked, will be extended. It was along the same level given a year ago.