Three Greenpeace activists were arrested Thursday afternoon during an attempt to stop the delivery of nearly 30,000 tonnes of coal to the Nanticoke power plant on the shore of Lake Erie, south of Hamilton.

The activists' storming of the ore carrier comes a day after the Ontario Power Authority released a new power plan that calls for more than $25 billion to be spent on nuclear power plants to ensure the province's electricity supply until 2025.

"We're trying to draw attention to dirty energy in the upcoming Ontario election, specifically coal and nuclear power," said Brian Cox, the Executive Director of Greenpeace Canada. "It is our belief that coal and nuclear goes hand in hand."

The environmental group says the plant is among the province's single greatest contributors to global warming and pollution.

"We want Nantico, which is responsible for many thousands of deaths every year from smog pollution, shut down as soon as possible," said Cox.

On Thursday morning, five members of the environmental group approached and boarded the Algomarine ore carrier using inflatable boats launched from the Greenpeace vessel Arctic Sunrise.

Spokeswoman Joslyn Higginson said that before boarding, the activists painted an anti-coal slogan on the vessel's hull that read, "No coal, no nuclear — clean energy."

She said the Algomarine radioed the coast guard to remove the activists, then veered away from the port to await the arrival of authorities.

Three of the five protesters proceeded to chain themselves to the discharge room, the area where the unloading of the coal takes place, Higginson said. Then Ontario Provincial Police arrived and arrested the chained protesters.

About 30 protesters also assembled in front of the plant to block the delivery.

Shawn-Patrick Stensil, one of the protesters, described the Nanticoke plant as "Ontario's worst climate criminal."

He said he asked the captain of the ship prior to the protest to ask him not to deliver the coal "to do his part for climate change." 

The Nanticoke station is one of four coal-fired plants in Ontario first targeted by the Liberal government for closure in 2007. But the government later pushed the deadline back to 2009 and then to 2014.

With files from the Canadian Press