Japan last year stepped up spending on clean energy at a faster rate than any other country, despite a drop in the world's overall investment, a study said Thursday.

China remained the top investor in clean energy in 2013 but steep cutbacks in the European Union contributed to an 11 percent drop in global investment in the sector, the second straight year it has fallen, according to an annual survey by the Pew Charitable Trusts.

Japan was a major exception to the trend, ramping up investment in clean energy by 80 percent year-on-year to $28.6 billion -- nearly all in solar energy.

Japan, which has virtually no fossil fuel resources, has been looking to diversify its energy sources after the Fukushima nuclear reactor disaster during the 2011 earthquake and tsunami.

Japan ranked third in investment behind the United States and China, which was by far the largest with $54.2 billion put into clean energy in 2013, down slightly from the year before.

China has set ambitious goals on wind and solar energy as concern grows over the growing Asian power's air quality and climate change.

China remains the world's top producer of greenhouse gases blamed for climate change. It has promised to reduce the intensity of emissions but not the absolute number.

The European Union, long at the forefront of efforts to fight climate change, saw steep falls amid austerity measures and questions over future incentives.

Investment tumbled 55 percent in Germany, 42 percent in France, 75 percent in Italy and 84 percent in Spain.

Britain was an exception, with investment growing 13 percent to $12.4 billion with more than half of it in wind energy.