Prime Minister Tony Abbott says Australia's coal industry has a "big future, as well as a big past" and predicted it will be the world's principal energy source for decades to come.

Mr Abbott also heaped praise on Japan in comments that come just days after China slapped harsh new tariffs on coal imports and will be noted in Beijing as negotiations on a China-Australia Free Trade Agreement move towards conclusion.

Industry has estimated the new tariffs could cost Australia's economy hundreds of millions of dollars annually, though it will be some time before exact estimates can be made.

"Let's have no demonisation of coal," Mr Abbott said on Monday.