SYDNEY (AFP) - Australia's largest city will be plunged into darkness for an hour on Saturday in an attempt at a world first blackout to raise awareness of global warming, organisers say.

A successful switch-off could then be copied by major cities around the world in a drive to reduce the greenhouse gas emissions blamed for climate change, according to international conservation group WWF.

European Union states agreed earlier this month on a binding 20 percent cut in CO2 emissions by 2020. Yet over 20 coal-fired power plants -- major producers of greenhouse gases -- are planned for Germany.

German Chancellor Angela Merkel has said measures for protecting the environment are a top priority during her six-month European Union presidency.

Germany and other EU-member states agreed on a binding reduction of carbon dioxide (CO2) emissions by 20 percent by 2020 compared with 1990 levels. The EU also proposed a 30-percent cut if other nations followed suit.

There's a hitch, though, for Germany, said Reinhard Loske, a member of the German parliament and climate expert for the Green party parliamentary group: Currently, up to 26 coal-fired power plants -- which would burn either hard (anthracite) or brown (lignite) coal -- are either being built right now or are in the planning stages in Germany.

"If all of those plants end up being installed, there is no way we can reach our climate protection goals for reducing emissions," Loske said.

Coal-fired power plants are one of the biggest producers of greenhouses gases, which scientists have said are primarily responsible for global warming.