The Queensland government has signed off on what could be the biggest coal mine in Australia and one of the largest in the world.

Deputy Premier Jeff Seeney told parliament on Thursday the proposed $16.5 billion Indian-owned Adani Carmichael coal mine project in the Galilee Basin had been approved by the state's coordinator-general.

The proposed $16.5 billion Indian-owned Adani Carmichael coal mine project in the Galliee Basin had been approved by Queensland's Coordinator-General. Credit:Rob Homer

The mine is still to receive federal approval.

But Mr Seeney said he believed it would serve a "vital role" in opening the Galilee basin, which is also home to Clive Palmer's proposed coal mine and the Hancock-GVK Alpha mine project.