Siemens will remain involved in the controversial Adani coal mining project, despite massive environmental criticism as Australia faces unprecedented bushfires.

The contract for almost $30 million calls for the German company to supply rail infrastructure for the Carmichael mine in Queensland, near the Great Barrier Reef.

"We have just finished our special meeting ... We have evaluated all the options and have concluded that we must fulfil our contractual obligations," Siemens CEO Joe Kaeser said in a message on his Twitter account.

Just finished our extraordinary Managing Board Meeting. We evaluated all options and concluded: We need to fulfil our contractual obligations. Also, we will establish an effective Sustainability Board to better manage environmental care in the future. https://t.co/uPgjPgwFrr — Joe Kaeser (@JoeKaeser) January 12, 2020

He also promised that Siemens, which supports the Paris climate agreement to curb carbon emissions, would create a body to better "manage in the future the questions of protecting the environment."

The proposed Carmichael mine, owned by India's Adani group, has long been controversial but anger over the multi-billion-euro project has been fanned by Australia's catastrophic bushfire season.

Activists from Fridays for Future and Extinction Rebellion staged demonstrations in a dozen German cities against the mine on Friday, including outside Siemens' Munich headquarters.

It seems that @SiemensDE have the power to stop, delay or at least interrupt the building of the huge Adani coal mine in Australia. On Monday they will announce their decision. Please help pushing them to make the only right decision. #StopAdani — Greta Thunberg (@GretaThunberg) January 11, 2020

The open-cut Carmichael mine is set to become operational next year and produce up to 27 million tonnes of coal annually.

The troubled project, which has been scaled down since it was first announced, has run into repeated delays caused by legal and regulatory hurdles, as well as funding problems.

Supporters say the mine will bring hundreds of much-needed jobs to rural Queensland in eastern Australia.

AAP

But conservationists say the project threatens local vulnerable species and means coal will have to be shipped from a port near the already-damaged Barrier Reef.

The world's largest coral reef system faces multiple threats to its survival, most notably rising sea temperatures caused by climate change, water pollution and coral-eating starfish.