BERLIN (Reuters) - Germans, who sometimes see themselves as guardians of the environment, are hoarding energy-guzzling incandescent light bulbs ahead of a looming European Union-wide ban, the GfK market research agency said.

The Nuremberg-based GfK reported sales of incandescent bulbs had soared about 35 percent in the first half of the year ahead of a ban that starts Tuesday -- even though it was proposed by German Environment Minister Sigmar Gabriel in 2007.

Some German retailers said they have seen sales of 100-watt incandescent bulbs soar 600 percent since the end of July.

The EU is planning to phase out use of the incandescent bulbs as part of its push to save energy, cut greenhouse gas emissions and fight climate change. From Tuesday the light bulbs above 75 watts can no longer be produced or imported in the EU.

The ban will be expanded each year and by 2012 production and importing of all incandescent bulbs will be prohibited.

The EU Commission projects the ban on the energy-inefficient bulbs will save about 40 terawatt hours of energy in the EU per year -- enough to meet the energy demands of a small country.

The idea to ban incandescent bulbs came from Gabriel in 2007 when Germany held the EU's rotating presidency. The German said the switch to energy saving bulbs could save about 25 million tonnes of CO2 emissions per year.

(Reporting by Kim Bode; writing by Erik Kirschbaum; Editing by Jon Boyle)