Australian climate change activists paralysed the world's largest coal exporting port Sunday for five hours by breaking into the site and chaining themselves to machinery, officials said.

The protesters, from environmental action group Rising Tide, sneaked into Newcastle Port north of Sydney before dawn and attached themselves to loaders in what they called "an emergency intervention".

"Operations were stopped from dawn through to mid-morning," a spokesman for the port told AFP.

"There was a total shutdown for a period of about five hours, (and) a disruption for a period of about eight hours."

It would be several days before the cost of the disruption was known, the spokesman said.

Police said seven men and two women had chained themselves to or suspended themselves from machinery, while another 32 activists stormed the Port Waratah Coal facility to occupy a coal stockpile.

"All nine protesters who were tied to the structures were eventually removed by officers from the Police Rescue Squad, arrested and taken to Newcastle Police Station," police said, adding that they had been charged with trespass.

Those who occupied the stockpile were also arrested, but they were released without charge and are likely to be fined at a later date. Cranes were used to move some of the activists.

Rising Tide spokeswoman Annika Dean said that coal was Australia's number one contributor to climate change and the port was used to "export global warming to the world".

"Forty-five ordinary people, of all ages and all walks of life, have come together today to make a stand for the future of our planet," she said.

"We were compelled to take these actions because our political leaders are failing to take any action at all."

The Port Warath facility is jointly owned by global mining giants Rio Tinto and Xstrata, both of which run extensive coal mining operations in the nearby mineral-rich Hunter region.

About 30 mines supply the facility, which is the world's largest coal export port with a capacity of 113 million tonnes a year. Hundreds of ships leave there each year for Japan, Korea, Taiwan, China and India.

Australia is the world's number one exporter of coal, last year accounting for a 28 percent share of the global market.