Queensland's mines minister says he granted mining leases for Adani's controversial coal mine after carefully weighing up the benefits and challenges of the project, including legal action.

Anthony Lynham said he pressed on with the leases for the $22 billion mine, rail and port project because it would create thousands of jobs.

An extra $200 million to $300 million would also flow into the state’s coffers every year in royalties, and that was based on current coal prices which were low, he said.

But his decision to grant the leases has drawn the ire of conservationists, who claim the project will further imperil the Great Barrier Reef.

Two groups fighting the mine in separate court battles have accused Dr Lynham of abandoning previous assurances that leases would not be granted until two existing cases were resolved.

Just eight weeks ago, Dr Lynham said he wanted to give certainty to Adani and “granting a mining lease in the presence of two JRs (judicial reviews) does not provide the certainty”.

Separate Federal Court challenges brought by the Australian Conservation Foundation (ACF) and the Wangan and Jagalingou (W&J) traditional owners are yet to be concluded.

The Environmental Defenders Office – which is representing ACF in its challenge to the project’s federal approvals – has already said it is considering challenging Dr Lynham’s decision to grant Adani mining leases.

When asked to explain why he had issued the leases despite the two outstanding challenges, Dr Lynham’s office said he had approved them after carefully weighing up the benefits and challenges of the project, “including legal action”.

Earlier he agreed there was a prospect of further court appeals.

“That is the climate we’re in today,” he told ABC radio.

But he said the Queensland government had restored objection rights to such projects and the government expected people to have their say.

More than 100 protesters gathered outside Queensland’s parliament to hit out at the state government for approving the leases.

“This is not over, we are still fighting this,” ACF spokeswoman Nadia Montague said.

Reef expert Professor Terry Hughes, the convenor of the National Coral Bleaching Taskforce, described approvals for the Carmichael mine as incredibly backward.

“And obviously the timing could not be worse in terms of the condition of the Great Barrier Reef from this bleaching event caused by global warming, which is mainly caused by burning coal,” he said.

But National resource industry employer group, the Australian Mines and Metals Association (AMMA), said the Carmichael approvals could not come soon enough for Queensland.

“This significant project should now be given full support for what it represents – a welcome boost for Queensland’s economy and jobs,” AMMA’s Scott Barklamb said.