Former Prime Minister Junichiro Koizumi on Saturday reiterated his call for Japan's complete exit from nuclear energy as the country marked the sixth anniversary of the Fukushima nuclear disaster.

"Nuclear power plants will become a negative legacy for future generations," Koizumi said at an event organized by a civic group in Sapporo.

The group is seeking the decommissioning of nuclear reactors at Hokkaido Electric Power Co.'s Tomari power station in the village of the same name.

"(Japan) can become a much better country with zero nuclear power plants, harnessing natural energy," Koizumi said.

Replacing nuclear energy with renewable energy will not be so difficult a challenge if technological innovation advances, he said.

After his speech, Koizumi lambasted Prime Minister Shinzo Abe's nuclear policy, which promotes restarting atomic plants — most of which remain offline — and exporting nuclear reactors.

"If the prime minister said 'zero (nuclear power),' the situation will greatly change. I don't know why he can't understand this," Koizumi said.