SYDNEY – Australian politicians told China of government approvals for a controversial A$16.5-billion coal mine project being built by Indian conglomerate Adani Enterprises, a panel of senators heard on Thursday.

Thousands of people turned out across Australia this month to protest against the project in northeastern Queensland state, which Adani has battled to try and get off the ground for years in the face of political and environmental headwinds.

Prime Minister Malcolm Turnbull's government faces flak from environmental activists who say its letter to China's powerful economic planner crossed a line in attempting to drum up funding for the mine, but the government says it stuck to facts.

"The Australian government continues to welcome foreign investment that is in our national interest, including the Adani investment in the Carmichael mine project," Attorney-General George Brandis told a Senate estimates hearing in Canberra.

Turnbull's Liberal Party, which holds federal power, and the Labor Party, which rules Queensland, have publicly supported the mine.

The government had made a representation to China "to dispel the misinformation campaign of those from the radical left," Brandis added, without revealing the date of the missive.

The letter, written by the deputy prime minister and the trade minister, described the grant of environmental approvals and government support for the mine because it could create jobs in rural Australia, he added, and provided facts, not advocacy.

Adani says the project will create 10 000 direct and indirect jobs.

However, the letter to China's National Development and Reform Commission crossed the line into "lobbying by Australia to provide ground funding for the mine," said Blair Palese, a spokeswoman for environmental activist group 350.org.

Campaigners fear coal from the mine will boost global warming and climate change while the massive seafloor dredging required to accommodate hundreds of ships in its location near the Great Barrier Reef may imperil the famed tourist attraction.

Adani has said it may seek financing help from foreign and Australian lenders, without identifying any candidates, and has sought A$900-million in Australian government loans to build a railway in Queensland to ship coal 400 km to a Pacific Ocean port.

Adani wants to tie up financing by March 2018 and would look to sell a minority stake in the project to help raise funds.

Adani spokesman Ron Watson said he did not think it was unusual for Australian politicians to confirm the status of a major project to a foreign country.

China is a large importer of Australian raw materials, including coal.

The $12-billion Sino iron-ore mine in Western Australia state represents China's single biggest overseas investment in the resources sector.