An environmental group said it blocked rail lines to Australia's main coal export port for six hours on Sunday, calling it a protest against the failure of the Copenhagen summit on climate change.
Rising Tide said its members chained themselves to tracks, hung from a bridge and climbed on trains to stop them reaching the Kooragang coal terminal in Newcastle, north of Sydney.
Australia is the world's largest exporter of coal and relies heavily on coal for its electricity. Much is mined in the Hunter Valley, inland from Newcastle, and mostly shipped from the port.
Spokesman Steve Phillips told Reuters the protest ended after 23 of the group's members were arrested by police. "Direct action," he said, was warranted in view of the failure of world leaders to address climate change.
"We did it as a protest against the failure of the Copenhagen climate change talks," Phillips said. "We are losing faith in our leaders to get the world out of this crisis."
Police confirmed 15 arrests but said that figure was likely to be incomplete.
UN climate talks ended in Copenhagen on Saturday with a bare-minimum agreement, with delegates "noting" an agreement struck by the United States, China and other emerging powers that fell far short of the conference's original goals.
Rising Tide, based in the area, has carried out similar high-profile protests. Spokesman Phillips said coal exports were targeted as they represented Australia's "biggest single contribution to the climate crisis".
The coal handling facility, focus of various protests, is operated by Port Waratah Coal Services, which calls it the "world's largest and most efficient coal handling facility".
A spokesman said the protests would have little impact on its operations, as it had large stockkpiles of coal.
"There is nothing to suggest there is going to be an impact on throughput," the spokesman told Reuters.
In 2008, the company handled 91.5 million tonnes of coal.
Major shareholders in the company include mining conglomerates Xstrata and Rio Tinto, through its Coal and Allied subsidiary.
