Seventy percent of the Japanese public supports centre-left Prime Minister Naoto Kan's policy to make the country nuclear free in future but most people still want him to quit, a poll said Sunday.

The weekend survey conducted by Kyodo News agency showed 70.3 percent support Kan's policy of ending nuclear power while 66.9 percent think the unpopular prime minister should leave office by the end of August.

Kan said earlier this month that the country must gradually reduce its reliance on atomic power with the eventual goal of becoming nuclear-free, despite fears that power shortages could slow an already limping economy.

The premier, a one-time environmental activist, has said he wants to make clean energy sources a new "major pillar" of the energy mix of the world's third biggest economy, which remains an export powerhouse.

His remarks came four months after a March 11 earthquake and tsunami triggered the Fukushima nuclear accident, the world's worst atomic crisis since Chernobyl 25 years ago.

The premier is under intense pressure to quit from political adversaries who accuse him of having bungled Japan's response to the tsunami which left around 22,000 people dead or missing.

Kan's scepticism about boosting nuclear power in the quake-prone island nation has also set him on a collision course with pro-nuclear lawmakers, both in the conservative opposition and within his own party.

The earthquake and tsunami crippled the Fukushima plant, which has suffered meltdowns, explosions and radiation leaks into the air, soil and sea.

With two-thirds of Japan's 54 reactors now shut, mostly for regular checks, the country is going through a power crunch in the sweltering summer months.