According to a survey called the "Dirty Thirty" by the World Wildlife Fund, Greece's Agios Dimitrios and Kardia plants (owned by DEH) are the continent's dirtiest power stations, followed by Niederaussem in Germany, which is owned by RWE.

In 2006 the Dirty Thirty were responsible for 393 million tons of carbon dioxide emissions, or roughly 10 percent of all EU CO2 emissions.

"The facts are clear: The power sector needs to phase out dirty coal as soon as possible," Stephan Singer, head of WWF's climate program, said in a statement.

More than half of the Dirty Thirty are run by just four power-generation companies: Germany's RWE, Swedish firm Vattenfall, French group EDF and Germany's EON.

"We cannot tolerate a power sector where the dirtier get richer," Singer said.

In an embarrassing detail, the study also exposes Germany, which in the past has positioned itself as a role model in the battle against climate change, as a home to a wealth of especially dirty plants, all of which are coal-fired. Only the United Kingdom can match Germany's 10 plants in the Dirty Thirty list (next is Poland, with four), yet not even Britain can rival Germany's six plants in the top 10.

RWE's coal plants in Frimmersdorf, Weisweiler and Neurath are ranked five; six and seven; two lignite-fired plants run by competitor Vattenfall rank four and 10 on the WWF's list.

Earlier this year German Chancellor Angela Merkel, who currently holds the EU presidency and the Group of Eight, managed to have EU leaders agree to ambitious goals to reduce greenhouse-gas emissions, yet the new study casts a dark shadow on Berlin's green advances.

"It's no secret that Germany partly works with antiquated power plants," Claudia Kemfert, the head of the energy and environment division at the German Institute for Economic Research, a Berlin-based think tank, told United Press International Friday. She added, however, that this was also due to the high importance of hard coal and the even dirtier lignite for Germany's energy sector.

The country has significant domestic lignite resources, and coal-fired plants produce roughly half of all German electricity.

German companies plan to replace many of the dirtiest plants with roughly 25 to 40 new, more efficient coal-fired plants, yet to the irritation of experts, they will still burn fossil fuels and emit greenhouse gases.

"If the companies build all those plants, we will have established a fossil fuel-dominated plant portfolio for the next 40 to 60 years," Kemfert said, adding this could even hurt Germany's economy in the long run. "I expect prices for CO2 emissions to rise significantly, and that means electricity produced from coal will become more expensive."

Germany does have a problem: It knows it should replace many of its aging coal-fired plants soon, yet feasible technology for an efficient "clean coal" plant still is some 15 to 20 years away.

Merkel has done much for climate protection at the EU level, and she plans to make climate change a main topic for next month's G8 summit in Heiligendamm, Germany. Yet domestically, Merkel, a former environment minister, has been less successful in her efforts to go green.

Her conservatives and climate-change experts have in the past lobbied for longer running times for the country's nuclear power plants, which are to be shut down by 2021 under a plan drafted by the previous government; Merkel, however, is bound to the phase out by the coalition agreement she signed when she became chancellor in late 2005.

Besides an extension of nuclear power, Berlin should also advocate energy-efficiency measures (which it does), and -- above all -- promote the use of renewable energy sources, Kemfert said.

"If Germany holds on to its 50 percent share of coal in electricity generation, it won't reach its climate change goals, and that would be embarrassing for a country aiming to be a leader in the fight against global warming," she said.