* Siemens says will provide rail tech to coal mine
* Environmentalists criticize Siemens for supporting coal mine
* Siemens CEO said company had a duty to fulfill contract (Adds detail from Siemens CEO)
FRANKFURT, Jan 12 (Reuters) - German engineering group Siemens said on Sunday it will fulfill its contractual obligations to a controversial coal mining project in Australia's outback, despite criticism by climate activists including Greta Thunberg.
Siemens was awarded a contract last year to provide signaling technology for a railway line to transport coal from a coal mine run by India's Adani Group in the outback.
The German company had said it would decide by Monday on its involvement in the project.
On Saturday Thunberg called for Siemens to review its role in the project.
"There is practically no legally and economically responsible way to unwind the contract without neglecting fiduciary duties," Siemens Chief Executive Joe Kaeser said in a statement.
Local and federal governments approved the project based on the Environmental Protection and Biodiversity Conservation Act 1999 as well as hundreds of pages of environmental impact statements, Siemens said.
"While I do have a lot of empathy for environmental matters, I do need to balance different interests of different stakeholders, as long as they have lawful legitimation for what they do," Kaeser said.
"Keeping our promises is Siemens highest priority. Only being a credible partner whose word counts also ensures that we can remain an effective partner for a greener future."
Environmental activists are concerned that the continued use of coal will lead to higher emissions of carbon dioxide, a gas which is linked to global warming.
Siemens said that it had pledged to achieve carbon neutrality by 2030 and it fundamentally shares the goal of making fossil fuels redundant over time. (Reporting by Thomas Seytal and Alexander Huebner Writing by Edward Taylor, Editing by Susan Fenton)