Indian energy giant Adani announced on Thursday that it will self-finance its controversial coal mine in Australia.

Major works on the 'scaled back' project will start 'imminently' after eight years of court challenges from environmental activists and delayed approvals, Adani Mining chief executive officer Lucas Dow said.

He said the Carmichael mine in Queensland would initially begin on a small scale and 'ramp up' to a capacity of 27.5 million tonnes a year — less than half the size of the approved project.

'We have finance and we are ready to start,' Dow said.

'Adani Mining's Carmichael mine and rail project will be 100 per cent financed through the Adani Group's resources,' he said, adding: 'We will now begin developing a smaller open-cut mine comparable to many other Queensland coal mines and will ramp up production over time.'

'Preparatory works at the mine site are imminent,' he said in a statement.

'We have already invested 3.3 billion dollar in Adani's Australian businesses, which is a clear demonstration of our capacity to deliver a financing solution for the revised scope of the mine and rail project,' he said.

The announcement of self-funding comes after environmental groups pressured banks in Australia and overseas not to lend money to the project.

'The project stacks up both environmentally and financially, Dow said.

Protesters in Brisbane on May 25, 2017. Shutterstock

The Indian energy giant has battled the opposition to any expansion of the Abbot Point port, saying it will cut into the Great Barrier Reef World Heritage Area.

Another major concern about the environmental impacts of the proposed mine has been that it would wipe out the most important habitat of the threatened black-throated finch.

'Today's announcement removes any doubt as to the project stacking up financially. We will now deliver the jobs and business opportunities we have promised for North Queensland and Central Queensland, all without requiring a cent of Australian taxpayer dollars. In addition to providing these jobs in regional Queensland, our Carmichael coal will also provide a power source to improve living standards in developing countries,' he said.

The Australian Conservation Foundation said the announcement meant Adani was a 'step closer' to building its mine, but called on elected representatives to intervene.

'This financing announcement means ignorance, denial or avoidance are no longer viable,' ACF chief executive Kelly O'Shanassy said. 'The only responsible response is to stop Adani and keep Galilee Basin coal in the ground. The Stop Adani movement will fight this proposed mine every step of the way. There is too much at stake. '

Adani acknowledged it still had some 'remaining required management plans' to finalise 'ahead of coal production' and that the process for those should be completed within weeks.

The group entered Australia in 2010 with the purchase of the greenfield Carmichael coal mine in the Galilee Basin in central Queensland, and the Abbot Point port near Bowen in the north.