Sydney, June 6 (IANS): Indian billionaire Gautam Adani on Tuesday said he had got the nod to open Australia's biggest coal mine. His company announced a "final investment decision" on the $16.5 billion Carmichael project.

"I am proud to announce the project has Final Investment Decision (FID) approval which marks the official start of one of the largest single infrastructure and job-creating developments in Australia's recent history," the Adani Enterprises Chairman said.

"This is a historic day for Adani, a historic day for regional Queensland, and a historic day for Indian investment in Australia," Adani said in a statement.

"This is the largest single investment by an Indian corporation in Australia and I believe others will follow with investments and trade deals."

Pre-construction work on the project in northern Australia is expected to begin in September despite protests from environmental groups, Australian media reported.

The announcement followed a mining royalties deal struck between Adani and the Queensland state government last week.

The Australian government said the mine will generate investment but critics say it will harm the environment.

Environment activists said the Carmichael coal mine project on the Galilee Basin in Queensland state will exacerbate global warming and pose a threat to the Great Barrier Reef, located in the same region.

"This mine will be a disaster for the climate, the Great Barrier Reef and frontline communities in Queensland and around the world," Greenpeace spokesman Nikola Casule said.

Adani hit out at green activists: "We have been challenged by activists in the courts, in inner-city streets, and even outside banks that have not even been approached to finance the project.

"We are still facing activists. But we are committed to this project."

Queensland Premier Annastacia Palaszczuk said: "There will be jobs right across the state. This project will deliver those jobs."

Resources Minister Matt Canavan also defended the project, which involves the construction of a 389-km railway line, at the inauguration of the Adani office in Townsville.

However, Environmental groups branded the announcement a "con" because Adani didn't secure the finance to reach financial close, the major hurdle to construction of the project, the Sydney Morning Herald reported.

The project, which plans to create 10,000 direct and indirect jobs, is yet to receive funding guarantee after four major Australian banks backed out.

In October 2015, the Australian government had re-approved the Adani project after a court ruled in favour of a legal challenge to the project, imposing 36 strict conditions.

The conditions included accepting the recommendations of independent experts to protect a habitat of 31,000 hectares and funding to investigate and protect endangered fauna in the wetlands of Doongmabulla Springs.

The mine, which could operate for about 90 years, will produce 60 million tonnes of coal to be exported from the Abbot Point port terminals, located near the Great Barrier Reef.