Adani, which estimates its project will generate more than A$22 billion ($15.6 billion) in taxes and royalties, has yet to line up funding but is sticking to a late 2017 start date.

The key hurdle Adani needs to clear to secure loans for the Carmichael mine, rail and port project is dredging approval to expand its Abbot Point port.

Australia's federal and Queensland governments are eager to see the mine built following the loss of more than 4,000 coal jobs over the past two years, but analysts and project finance experts believe Adani may have underestimated the challenge of raising funds for the project.

The mine, designed to eventually produce 60 million tonnes a year of thermal coal used in power stations, has been the focus of opposition by green groups fighting new coal mines and the rail and ports needed to ship the coal.