Dozens of protesters shut down the railway line leading to Australia's biggest coal export facility on Sunday, in protest over what they said was the failure of global climate change talks in Copenhagen.

Some 40 activists with the environmental group Rising Tide Newcastle stopped a coal train and chained themselves to it and the rail tracks to effectively close the line at Newcastle north of Sydney.

"A number of arrests have been made," a police spokesman told AFP.

Rising Tide said 23 people were arrested as the protesters were removed from the human blockade, which they said shut down the line for six hours.

The group said its action was triggered by the outcome of the UN climate talks in the Danish capital, which even UN chief General Ban Ki-moon admitted had failed to win global consensus and would disappoint many.

"The US, Australia, and other wealthy countries wrecked the Copenhagen climate talks," said protest spokesman Steve Phillips.

"They refused to lift their paltry greenhouse pollution targets to the levels required to avoid catastrophe.

"They could have done something great, but they failed. They let greed and self interest take precedence over the survival of life on earth, and we are here today to condemn them in the strongest possible terms."

The group said coal exports from Newcastle were Australia's single biggest contribution to the climate crisis.

Australian Greens leader Bob Brown said the coal industry, a major contributor to the Australian economy, should be prepared for more protests.

"Civil society is getting more and more frustrated and angry with the inaction of the pollution-bound, big-party politicians," he said.

"We are going to see more protest action against the powerful coal mining lobby, which wants to open more coal mines."