Green party parliamentary group leader Renate Künast said the critical situation in Japan has cast new doubt on the government's push to delay phasing out nuclear power.
In an interview with broadcaster Deutschlandradio Kultur on Saturday, Künast cautioned that although Germany is not a quake-prone country, "we do not control nature, rather nature controls us."
Friday's devastating earthquake in Japan has left at least hundreds of people dead. Officials said radioactivity was recorded outside the Fukushima nuclear plant following a large blast at the site, sparking fears of a meltdown.
Künast said the catastrophe has raised questions as to whether faulty decisions on the nuclear power issue have been made in Germany – pointing to the coalition government's move to allow existing reactors to run well beyond the planned shut-off date around 2020.
A planned demonstration on Saturday between the Neckarwestheim nuclear plant in southwestern Germany and the city of Stuttgart was expected to draw some 40,000 protesters.
The quake in Japan has also prompted members of the socialist Left Party, as well as environmental groups, to voice their opposition to nuclear power in Germany.
The head of the Left party Klaus Ernst told the Saturday edition of daily Leipziger Volkszeitung that atomic power is "simply not controllable."
"In densely populated areas, it is perpetually playing with fire," he added.
Japanese Prime Minister Naoto Kan has declared a state of emergency at the Fukushima plant. An area around the facility was evacuated due to the potential that failure of the cooling system could lead to a meltdown.
"Ausgestrahlt," an organisation opposing nuclear power in Germany, said German plants are not immune to those risks, pointing to a 2004 incident at the Biblis plant in the state of Hesse.
"What we are witnessing in these dramatic hours is that even an automatic shut-off mechanism does not protect against a nuclear meltdown," said the organisation's spokesman, Jochen Stay.
Henrik Paulitz from the group International Physicians for the Prevention of Nuclear War claimed atomic power plants in Germany are not properly equipped to handle the threat of earthquakes.
He said it was probable that "all nuclear power plants in the Rhine valley and near the Neckar river are at risk of possible earthquakes in these areas."
Last month, an earthquake measuring at least 4.4 on the Richter scale shook the Rhine-Main region, but geologists said quakes of such magnitude are rare in Germany, and relatively insignificant on a global scale.