A total 32 people were arrested and charged with "marine-related" offences on Saturday and early Sunday at the Port of Newcastle, a major deepwater gateway north of Sydney, police said.

Several activists engaged in "unsafe practices" on the water during the protests, New South Wales state police said, warning that they had a "zero-tolerance" approach to threats to public safety or the safe passage of vessels.

Organisers Rising Tide said the weekend protests, in which flotillas of kayaks entered shipping channels, had forced two coal ships to turn around instead of entering the port.

Nearly 100 people in 50 kayaks entered the shipping channel again on Sunday, it said.

Greenpeace said activists climbed the side of coal ship Yangze 16 on Sunday and displayed a banner reading: "Phase out coal and gas."

Police landed in a helicopter on the ship's deck in the early afternoon and detained two activists after the seven-hour action, the environmental group said.

"As the world's third-largest fossil fuel exporter, Australia plays an outsized role in the climate crisis," said Joe Rafalowicz, climate activist at Greenpeace Australia Pacific.

He urged the centre-left government of Prime Minister Anthony Albanese to set a timeline to phase out goal and gas and stop approving new fossil fuel projects.

Greenpeace "stands with all peaceful climate defenders who are advocating for real climate action at the Blockade, and all around Australia", Rafalowicz said.

A spokesperson for the Port of Newcastle said shipping schedules continued over the weekend with the final vessel leaving in the afternoon.

"Vessel operations will continue tomorrow as scheduled," the spokesperson said.

Australia's parliament approved new environmental laws Thursday requiring large carbon-emitting projects to disclose their greenhouse gas emissions as well as pollution reduction goals.

But the Climate Council NGO expressed concern that the laws did not require the government to consider a project's climate pollution when assessing whether to greenlight it.

Despite heavy investment in the renewable sector, Australia remains dependent on its fossil fuel economy for growth.

It is one of the world's top coal exporters, holds the third-largest coal reserves and continues to channel billions of dollars in public subsidies to fossil fuels.