Hamburg - The state of Hamburg granted regulatory approval Tuesday for one of Europe's biggest coal-fired power stations, angering the environmentalist Greens Party which had campaigned for a gas plant instead.

Swedish-based utility Vattenfall has already begun construction of the 1,654-megawatt plant, which will burn imported hard coal and use river water for cooling.

The site at Moorburg in Hamburg's port has become a bugbear to European ecologists, who charge that coal is the culprit in global warming. Greens in Hamburg state's ruling coalition tried to block the project.

The decision is expected to strain relations within Germany's first coalition government combining Christian Democrats and Greens, two parties who are normally bitter foes.

Anja Hajduk, the city-state's environment minister and a Green herself, said she had granted the clearance because she had no legal power to stop Vattenfall, but would sharply limit its rights to use cooling water.

She said that rider would mean the plant's two generators would have to operate at less than full steam for 250 days per year. The 2-billion-euro (3-billion-dollar) project is set for completion in 2012.

Vattenfall says the modern plant will release 750 grams of carbon dioxide per kilowatt-hour of output, 200 grams less than older coal-fired plants. Supporters said the site would lessen German dependence on Russian gas.

The electricity company, which also operates nuclear plants in Germany, said it would lift the energy yield from coal to 46.5 per cent at Moorburg by using waste warmth to heat homes and factories in the city. (dpa)