Protesters in Sydney in early 2015 demand Australian banks end funding for coal port expansion in the Great Barrier Reef World Heritage Area

The coal industry is losing the public relations battle against environmental activists, mining giant BHP Billiton has warned as it urged the sector to unite to fight back.

BHP president Mike Henry said mitigating greenhouse gas emissions was essential, but it was also crucial that access to reliable and affordable energy was available to support development.

"It would be fair to say that as we stand here today, in the court of public opinion, the 'no coal' camp has been more effective," Henry said in the text of a speech he delivered Friday.

"Anti-coal activism has been building momentum over many years."

Coal is a key export for Australia and the industry employs thousands but the fossil fuel has been the focus of strong environmental campaigns.

Australia's city of Newcastle, which claims to be the world's biggest coal export port, last month said it will pull money out of fossil fuel industries and invest in more sustainable enterprises.

While a massive India-backed mine project in Queensland state, which environment groups say will exacerbate climate change, has been held up by a legal challenge, prompting a call from the government to end the "sabotage" of coal developments.

Henry said he recognised that "some groups are determined to shut coal down altogether, and they have a clear strategy to frustrate and delay coal and gas projects".

Coal is a key export for Australia and the industry employs thousands but the fossil fuel has been the focus of strong environmental campaigns

"And while their near term impact on actual investment and policy is arguably limited, they are certainly influencing public perception," he said in the speech to the American Chamber of Commerce in Brisbane.

Calling for the industry to coordinate its efforts in influencing the debate, Henry said thermal coal was expected to play an important part in meeting the world's energy needs, especially in Asia, rejecting the idea that coal use will be phased out in the next two decades.

As the world prepares for climate talks in Paris later this year, Henry said the industry must come together to adopt a more "unified, balanced and credible view in respect of ".

© 2015 AFP