The Sydney Morning Herald reported 15 activists entered the station at dawn this morning and switched off power to the conveyor system before painting "Coal Kills" on the station's roof and chaining themselves to equipment.
In a statement released by Greenpeace today the organisation explained the "peaceful direct action" was in protest to both John Howard and Kevin Rudd's "dismal climate change policies".
"Greenpeace is demanding that both major parties commit to deep cuts to Australia's greenhouse gas pollution in the next decade, which means switching from coal-fired power to cleaner and smarter energy use," said the environmental activist group.
It added that all staff at the power station had been evacuated early this morning and a huge banner stating "Climate change starts here" has been hung inside the station.
The SMH said four of the 15 protesters have been arrested by police, who have called in the police rescue squad to unchain the activists and requested the support of the Public Order and Riot Squad.
Protest leader and Greenpeace Australia Pacific energy campaign manager John Hepburn said the first step to greenhouse gas emission reduction is switching from coal plants to energy efficient and renewable sources.
He said Munmorah is the oldest and least efficient station in NSW.
Hepburn told the SMH that he would not reveal how the protesters entered the station for legal reasons.
A representative from station operator Delta Electricity told the SMH that the protest does not affect production at the plant and that the company is focused on preventing damage to property or injury to staff while the activists are at the plant.
The protest not only ties in with Australia's federal election but also the release of a US-based report, released by the Centre for Global Development, that revealed Australia's energy companies emitted the worst rate of greenhouse gas per capita than any other country.
Listed among the world's 100 worst power stations in the report - How Green Is Your Power? The Case For Public Disclosure of CO2 Emissions - are the Bayswater and Eraring plants in the Hunter Valley of NSW.
