Merkel, speaking to the Bundestag, the lower house of Parliament, urged Germans to donate money to help Japan rebuild following last week's 9-magnitude earthquake and tsunami that damaged the six-reactor Fukushima Daiichi nuclear plant, the BBC reported Friday.
"This is help between friends," Merkel said.
She also said Germany should redouble its efforts to develop safe renewable energy sources.
Merkel said Germany's nuclear power plants are among the worlds safest, but "when, in Japan, the apparently impossible becomes possible and the absolutely unlikely reality, then the situation changes."
The nuclear crisis in Japan has countries around the world reassessing the safety of their nuclear power plants.
Bulgaria is considering a freeze on a nuclear project near a seismic fault line and France, the worlds most nuclear-dependant state, has ordered tests on its 58 reactors.